So what's your suggestion for how YouTube could be doing better here?

Especially in the scenario that (as the top level comment in this thread suggests) YouTube didn't actually make any changes and the reason the views dropped is because EasyList added an entry to their privacy filter. Should YouTube have recognized that they're in a quasi-monopoly position as you suggest, done the research to identify EasyList as the culprit behind the view metric drop, and then released a change to their client to add a new endpoint which isn't blocked by EasyList?

We don't know that the EasyList theory is what's really going on here, but if you're going to tar YouTube/Google over this ordeal, then I think you have some responsibility for suggesting how they could have done better.

YouTube can’t “do better”; the problem is the monopoly (their moat is too damn wide).