Longer version: Do you know any of these Bronie types? My daughter befriended one at the beginning of the school year. She didn't know he was one at first, which would have been a sign to run for the hills. He looks just like the boys in the "Bronie convention picks" and my Spidey senses warned me something was off about this guy when I first saw him.
But he was seemingly polite and funny and they got along well due to an affinity for video games. He wasn't the best looking boy, a bit overweight, insecure, etc., but I figured if he was a decent boy there was nothing wrong with being platonic friends.
Within a few months she learned he was was an emotional basketcase. I won't go into details, but it was bizarre and hurtful to her. I supposed he developed a crush on her, but she just thought of him as a friend and he lacked the social skills to deal with this. (I homeschooled my daughter for 8 years so I know all about "socialization" issues garbage).
He was moodier than any of her female friends and lacked any emotional maturity to communicate on anything but the shallowest level. Pop culture was all he was interested in, to a a degree that it weirded my (very accepting) daughter out. This stupid cartoon and video games and anime was an obsession to him, unhealthily so.
I understand teenage boys through the ages have all had their hobbies: sports, Star Wars, cars, etc. But the degree to which these Bronie-types are obsessed about a girl child's cartoon in not quaint or innocent. Do you know that there Bronie types frequently talk about which cartoon horse they would prefer to have sex with?
Cartoon characters like Betty Rubble, She-Ra, Wonder Woman, Turangaleela, I get. It's bizarre, but I get it.
But when a teenage boy starts to fantasize about banging cartoon horses to the extent that there is porn and fan-fiction out there about this, I would say there's nothing innocent about that!
After rereading your comment I think I might be able to help you ran into a person who was obsessed the target of the obsession really didn’t matter all that much as a person who truly obsessed is almost by definition going to have personality issues.
To put things in more classical language you are confusing cause and effect.