I recommend Shirobako and Barakamon, both very art related anime.>>3235439
If you don't think something should be taken seriously, then don't take it seriously. That's one of the better things about the anonymous thing; it forces you to analyse each post on its own merits, rather than taking someone's word as law when you see that they're some famous pro, or completely ignoring someone who's on a similar level to you.
People being told their art is shit can be down to anons being obsessed with very high standards, so if something doesn't look like it was made by Mullins with glistening perfect anatomy then it's not good enough. Or, it can be jealousy and they're salty about the person getting better or getting attention so they shitpost.
Don't take anything too seriously I guess.