While I agree largely with your conclusion that anti progressive ideas are pushed to undermine progressive spaces, I don't really agree with how you get there and with the examples you choose to arrive at that conclusion. There obviously are actual bad actors, and actual hegemony to get these bad actors into being, but there is also a lot of real people, actually still learning about the topics, or just plainly with a different perspective on some of the issues that you might be discussing.
For it to be an ideology that is self consistent leftism actually needs differences and disagreement, or said in another way: if we were to prescribe beliefs instead of trying to teach them we'd also just be trying to build our "own" authoritarian hegemony. I can invoke successes of or defend the CCP and the soviets just as I can invoke successes of the US or EU or India realizing that all states are fundamentally bad, still sometimes perhaps by accident they do good things. And that examples and mental shortcuts, as well as actual experiments that might be of a socialist nature, are just what they are argumentative tools.
I've been called a tankie just because I see the downfall or backsliding of the US as good thing and don't really accept that china would be as bad as the US has been for the last 40 years or so. Which is perfectly normal for someone who doesn't really reap the benefits of US hegemony, and sort of just ranks authoritarian institutions by size(strength)(wealth) to arrive at a measure of subjective dislike.
It's almost similar to someone calling me a tankie because I purchase Pepsi instead of coca cola on that given day, when we all know I should make my own tea or at least just buy the supermarket/local brand to begin with.
I don't know where you are and what kind of people you meet on a regular basis but to me the simple and fast ways of understanding other people almost never hold true, most of us humans just lead to complicated lives to easily subjectify us. And honestly I wish most leftists would not try to subjectify other people to begin with.
Well some leftists would loose a lot obviously, specifically those in or directly around the US, but fascist regimes are not very sustainable, and certainly loose the ability to ally and coerce over time.
And This loss of ability to project power (by the largest and thus likely the most destructive institution of coercive power) is what I see as a critical step towards a communist or just any different way of economic and political organization on a global scale.
I don't want a facist US regime, I would never tell any leftists to advocate for one, but I would tell them to prepare or flee nonetheless because it is still likely, or at least possible that it happens (again).
I'd much rather have a reasonably progressive US voluntarily give up power in good faith, curtail her own economic might to allow her citizens a good life and our shared world a sustainable economy and ecology but given that among many other titles, she also holds the title of the foremost petrostate, and at least one of the largest Tax heavens, in the world I unfortunately don't really see that happening, I still hope for it, but as far as I understand powerful interests aligning and climate change, the world economy... it just doesn't seem particularly likely.
I'm in Germany so not anywhere extremely tied into the US, but at the same time both are imperial core, there is a lot of cooperation, I would likely feel a lot of the secondary effects, but I also believe perhaps naively that not all of the world would , blindly follow the US in it's slow march towards fascism. And with each institution peeling of from US hegemony there is at least a chance to throw a big political lever in the rightish direction, whether it be the EU, IMF, Nato or whatever else, a movement that at the moment is blocked largely by US and perhaps wider western but also sometimes chinese or russian imperialist positions. And of course the Capital that these states (actually) represent.
All of this is already happening anyways, murdering political opponents internally as well as outside of the US,furthering climate change, destabilizing and undermining trust etc. again sliding into fascism is not what I want, but even a fascist US would be bound by physical, organizational, and social circumstances, and thus for the wider world likely less catastrophic than you might believe it'd be if you were raised or resided in the US.
I can't claim for certain that the US is having a Weimar moment, and I cant be certain that a US fascism in the modern era would be shorter and less gruesome, I also can't say it'll be better afterwards, but I feel all of these things to not be completely outrageous predictions, because as leftists probably should, I can try to interpret the historical Weimar moment, and the current political landscape...
Well again, ramp up in war and climate change are already happening, and in my world the wars are already the 20th century ideas as well as their capital, lashing out against 21st century thinking, changes in circumstances, and the very real onset of this era of climate change scarcity that we are entering.
So to some extent from my point of view yes, you don't have to keep trying to be a democracy with institutions and foundational texts as well as family hierarchies from the 18th century, that were made and changed by your political enemies, you can fight for (but hopefully mostly against) the fascism that the powers at be try to impose upon you, but without just believing the popular vote, and the systems it enables, will save you here.
If you crawl out of an actual civil war esque partial collapse as hardened syndicalists, or if you can get rid of FPTP and establish a democratic socialist party that is able to actually make international agreements in good faith, for me it mostly doesn't matter. I'd prefer the second if I look at the human cost of both options, but because the first option I'd guess could be faster in implementation, and the result would be similar from an international perspective, I don't completely hate it, very literally I could likely "live with it", precisely because I likely won't have to live under it, much more than anyone from the US could.
Essentially I don't identify with the US emotionally, I have almost no image of her institutions being good, so I can compartmentalize and write off that particular nation state much easier. For me a fascist or civil war ridden US that is short lived and likely reemerges with better bones might actually be very similar to one that transforms more amicably.
I can just say suffering is going to be inevitable, but that the suffering to change things for the better, to make them work sustainably, to make them work for the people, is the one i hope Americans actually still strive toward deep down, because I by pure circumstance don't need to suffer in that same way, I will suffer differently and for a different reason, fighting essentially the same fight sure, but from a different position with different levers to pull and different pressures to withstand.
We had fascism here openly 80 years ago, it's still here trying it's hardest to grab power and survive, but perhaps obviously it's fastest decent, its quickest downfall was almost the exact same time as it's most emancipated period, in fact they followed each other in lockstep.