I think a lot of people take the opportunity and run with it. I’m not saying everyone is like this and I’m no psychologist but when I was in a self harm state (3 years ago) I remember being overly positive to keep people from asking questions because I believed no one understood me or would really care. So I’m guessing a lot of authors take that mindset and put it on Mikey.
He is typically portrayed as the youngest so that does put him under a lot of pressure to live up to Leo, Donnie and Raph,,
But then again, I’m not the only TMNT author out there, I don’t know the true reasoning people run with the self harm trope.