Yea it's pretty common, hence why I liked that they immediately crap on the trope by using Bakugou and Aizawa to show that no, you shouldn't go easy on her just because she's a girl. (Something that Tokoyami arguably did himself in a previous fight) That being said, it is also a thing that's undeniably intertwined with the respective characters, because like you said, it's a poor matchup at the end of the day, with several characters finding it additionally problematic because she's a girl.
The way I saw it, was if Bakugou fought a girl that people were aware could clearly rival him or considered to be better than him, perhaps people would be less inclined to say something. But since the matchup is a poor one, they don't just simply see that, but also "Omg, Bakugo is being a unnecessary jerk to this poor girl". At the end of the day it's just this irrational bias that can pop up whenever, regardless of the girl's strength. I also don't think it being a universe where (most, but not all) people have powers would make such biases suddenly not exist. Especially since quirks haven't existed since Day 1 meaning it's a relatively recent phenomenon, and everyone has different powers with varying degrees of usefulness. If anything, more biases have been created.
Maybe it would have been better for them to not bring it up at all, but considering the demographic the manga's marketed to, they probably need this spelled out for them lol