I'd pick reader insert fics over that godforsaken app or any other ai app that has roleplaying in it because:
reader insert fics are written by humans for humans.
plot that can be tailored according to what you want/what you requested from the writer or what the writer posted.
Accurate character representation or close enough to them, hcs are cool too.
reader inserts can be platonic and sweet and totally innocent without undertones or attempts of grooming.
Writers appreciate your comments and likes on their works, c ai just exploits your loneliness and is filled with ads and makes your attention span shorter.
human Writers don't cause increased carbon emissions and water use in addition to electronic waste.
human writers know about your and their comfort character well enough to write about them unlike ai that leeches off fan content and on top of that make a poor acting of said character.
reading a fic can actually increase your vocabulary and linguistic bank (especially if english is your second language, or any other language the fanfic is written in it)
fanfic writers don't collect your personal data or risk your privacy
Writing fanfics is basically a practice for characterization, world building, research on different topics or simply a good coping mechanism.
When reading fics you actually appreciate the work instead of wasting your emotional capacity on bots that wear your beloved character's skin.
Fics are real and cool no matter how badly written or ooc they are. they're the best and fandoms' gift to the world, and on top of that? they're free.