Because we aren't talking about anime in general. We are talking about one specific person's personal experiences with the subset of anime they watch.

If I say "she" when talking about generic protagonists in some Miyazaki films I've seen, are you going to say I'm wrong and should say "he" instead because some genre of anime I've never heard of is popular with some demographic I'm not a part of?

If that's really how you think, then do you also opine that we should say "she" rather than "he" when talking about generic human beings, seeing as women outnumber men? Somehow I suspect not.

Is there much Shonen that you'd describe as "heartwarming", though? I like stories about personal emotional growth, and magic. Wasn't using "she" for virtue signalling, just as what seemed to me to be a statistical fact. There's one I can think of with a male protagonist, and his great aspiration in life is to be murderer, and he targets his classmate, who is a tall and slightly dim-witted model ... and ends up filled with protective feelings toward her, which begin when he impulsively lends her his intended murder weapon (a boxcutter) to cut some card for a school project ... and by the end of the series they're going round a mall together at Christmas, holding hands. That was a pretty good one. Recommendations for ones with male protags are welcome, if they're not full of tanks and battles and so on.