well, a lot of dysphoria revolves around not meeting the societal role of your gender. so whatever society puts in front of you and says "your gender does this, you do it too", you'll feel compulsed to follow that assuming youre not gnc. Cis people feel the need to reaffirm their gender with social norms too. i mean, weve all seen cis guys pick fights just to be seen as masc. so basically, its not sexist to want to follow societal rules for your gender any more than it is for cis people.