You might have seen a quest, where if you stream a specific game to your friends you get a free in-game item, but these are not advertisements.
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Advertising is the practice and techniques employed to bring attention to a product or service. Advertising aims to put a product or service in the spotlight in hopes of drawing it attention from consumers
I have no interest in streaming "quested" games, and whatever deal Discord has done with the developer to encourage users to engage with such games (and by extension the game's microtransaction economy), and regardless of what they call it, is by definition an advertisement. If you can't see that, then you are an ad campaign exec's wet dream. Either that, or a troll.
Honestly, I am surprised it took them this long. This technology has existed for a while, there is even a standard for it (see: SCTE-35).
The harsh truth of the matter is that YouTube is a victim of its own success. The sheer scale of what is needed to keep the platform running at its current level of activity is something that I think most people don't give a second thought to. It requires a truly astonishing amount of technical expertise, infrastructure, monitoring, throughput capacity, not to mention sheer compute and storage, to keep it running. And that is considering the technical side alone, never mind the business that has evolved around it
All of the above costs money. A lot of money. So much money that only a shitty mega corporation with no moral scruples would ever be able to afford to run the platform, let alone turn a profit. And so here we are.
There are niche alternatives like PeerTube, but in practice it is currently in no state to be a drop in replacement. If the fediverse had to deal with the amount of traffic and content from YouTube in its current state, it would collapse immediately. This won't change until the user base begins to increase, but to do so requires an incentive for people to jump over. And sadly, far too many people just don't care enough about avoiding ads to do so.
I think in the long term there will be a reckoning; no matter the size of your platform you are not invulnerable to change. Nobody back in the early 2010s could foresee Twitter falling from grace, and look how that turned out. YouTube will eventually die, the only question is who will be footing the bill for what replaces it.
In the meantime, if you're unable or unwilling to deal with YouTube's ads, or pay to skip them, then just don't engage with the platform at all. Read a book. Touch some grass. They haven't found a way to monetize that (yet).