It sounds like you're disparaging the art (and in fact the artists for producing it) because you think it's not sufficiently technically difficult. It also sounds like you believe the artists are trying to present it as more than it is. But tell me if I've misunderstood you.

This is a very antagonistic attitude. You're approaching art with an adversarial mindset that only recognizes it if it's something nontrivial. I don't think anyone is trying to bullshit you - art is just subjective.

For many people, what's more important than the competence is the originality. Not even necessarily the originality of the thing itself, but of the meta surrounding it. In that sense, plain white canvas in a museum is actually pretty original. It's certainly less derivative than a lot of the highly competent also-rans who painted the same scenes in the same (highly proficient) styles in the same time period. Moreover, it made you think. You didn't have a positive reaction to it, but then (as any artist would tell you) art doesn't restrict itself to positivity :)

Now with that in mind, let's circle back to your other statement:

> You're supposed to have some kind of ability and that ability shouldn't have to be defended by pointless platitudes.

It seems like they do have an ability, it's just not an ability you respect because your definition of art is more narrow than theirs. And that's okay! No one is forced to deeply appreciate all forms of art. But the way you're disparaging this kind of modern art is a perfect example of the middlebrow dismissal that's already been brought up in this thread.

People are not full of shit just because you don't appreciate the (highly subjective) things they do. The triviality of many modern art pieces is part of a broader context which your criticism completely fails to capture.