I also don't get the "You have to fit in a bucket" theory. What's an example you've experienced?
But the trend being described here is exactly that. Affirmative action, curtailment of free speech etc. Even many diversity initiatives.
It doesn't matter if it discriminates positively, contrary to society's past regressive discrimination. This positive discrimination goes against liberal principles.
Straight from the mouth of Joe Biden: "If you don't know whether to vote for me or Trump you ain't black." Yeah, because a near-80yo white man is obviously the final arbiter of my ethnic identity if I don't conform to his politics.