How would they enforce this on open source projects without companies behind them?

This doesn’t require the user to be able to block, it’s required that there is the ability to block a user from the system in general.

They have been making a profit on YT for years already. This isn’t to cover the server cost, its to increase the bottom line after all competition was crushed by them. Also, I remember a time with unobtrusive ads that were fine and not an issue, unfortunately for the past 2 years or so they’re pushing more and more ads lately doubling up on them as well. Clearly people - just like me - start fighting back and stop them from abusing with massive amounts of unwanted content.