This doesn't really change your point at all, but I remember reading the tech news surrounding the Twitter sale to Musk as it was happening. If memory serves, Musk literally made the $420/share purchase offer as a joke, a joke that several lawsuits were filed to decide it was a serious and legally binding offer.
He memed his way into owning Twitter against his will, and then burned down everything to assuage his ego. But because he's a goddamn billionaire there are literally no repercussions.
Echo chambers are not dependent on having an algorithmic feed. It just matters that the people you talk with and the information you consume, etc, filter out dissenting opinions from what you hold.
Lemmy is still very much an echo chamber simply by virtue of the people who tend to be here. But we can balance that with time spent on other platforms, IRL relationships, etc.