Remember that the main reason the Protagonist has all the Exercise knowledge she allegedly does is because in her previous she had body/strength envy over the Hero who is the Ancestor of the Royal Family but just never used it in her last life because she wasn't "Blessed" with strength like him. So, idiots in this country might just high key see high Physical Strength as a Royal Family thing and just don't bother training in it ever so they don't realize its as much of an effort as magic.
That's incorrect, or at least not what the author is saying explicitly enough.
MC in his past life, as a guy, a commoner, knows (possibly along with eveybody else because it's common knowledge) that physical strength has a cap for non-nobles whereas magic don't have such a cap. So he could only ever max out on magic whereas he envies the hero who can max out both.
So when he reincarnated as a noble with maxed magic carried over, obviously he's going to max his strength now he's given his wish.
But because he's reborn as a girl and understandably noble ladies shouldn't be training muscles because close quarter combat is for men, which is why her brother is still training it as part of his education. So if he was reborn as a guy it would be no problem for him to muscle train all day and be strongest ever and the next hero.
So it's quite literally patriarchy's fault and that is an acceptable setting for a story.
But this whole premise falls apart, and is my original complaint...Is that okay we accept it's unladylike to be a musclebrain, leave the close quarter combat to the boys. But when she already demonstrated she's undeniably strong as fuck, you don't go antagonise her as if if you simply needed to pretend she is not strong then suddenly she won't be able to snap you in half.
Example:
When she's still weak and she is swinging a sword. You can go bully her, call her armored princess as a mockery because she's unladylike and is uncouth and uncultured like other nobleladie, what are you doing with a sword? Go learn magic like everyone else you weirdo.
When she waves her hand and slaps away high level magic aimed at her and she can walk towards you and there's nothing you can do to prevent her from reaching you and kills you with a swing. You don't bully her.