Even if you pay for YouTube premium you might still want to have adblocker on simply due to privacy concerns. Tracking is pervasive.
Infrastructure might not be free, but for many, many years these companies built their hegemonic position by pretending it was free. Now they pull the rug under people.
Tell me though, what alternatives there are for people who want to watch long form videos there are? Yes, you have nebula and a couple more; but YouTube is still king. In many cases watchers don't get to choose the platform. So yes, they could simply stop watching. But it's not an ideal situation and all because you don't agree with the way the platform earns money.
I think people should use adblocker. The way these platforms monetise our data is not something most of us chose, and the option to circumvent their practices is out there. It's a cat and mouse game, and we'll see who comes out on top.