People who act like you can't have an opinion on things you can't do

Drives me crazy when people tell me "I'd like to see you do better" when I state my opinion on something.

If I say I don't like an art piece, I shouldn't have to prove that I can make better than that. It's typically going to be better than anything I could make. Doesn't mean I have to like it. (Disclaimer: I won't just go up to a friend's drawing and tell them I don't like it. This is more for when I'm at say an art museum or contest of some sort)

Or when my sister cooks something and gives me some. I'm not able to cook well at all, but if I critique it at ALL, she says that it's better than what I could do. Like that's not the point??

ETA: I don't just bring up my critiques randomly. I bring them up when I'm asked.