I think this is common to most languages: English speakers lecturing native speakers about how they're grammatically incorrect based on some rule printed in an entry-level language textbook.

I once saw a white dude confidently assert to a Japanese person that 全然 could not be used in the positive and only in the negative. Dude wouldn't even back down after the Japanese speaker got out their phone and showed him a famous 12th century (or something) poem that used 全然 in the affirmative. That's like trying to correct someone's grammar and then getting shut down by Shakespeare.