Gaming culture is kind of weird that way. Especially in school, kids are very picky about establishing what is seen as cool and uncool within each group. Liking certain genres of music is pretty similar. You're cool if you like rap with one crowd. Another crowd thinks you're like savage and tough if you like metal. People in school would often pursue listening to artists/genres in order to impress the crowd they're trying to fit into. It's a time where people are sort of trying to figure out what their crowd is, so if you're too individual with your interests, I believe your peers feel threatened by that. A lot of gamers in high school turned to shooters because that was what was deemed "cool" at the time. Minecraft was another game that was apparently something the cool gamer kids were playing. Anything affiliated with Nintendo is usually just kind of dismissed and laughed at because it doesn't appeal to the "hardcore" audience, and if you're trying to look cool to people, you gotta come across as being into all the hardcore stuff.
There could also be some discrimination at play, though it's really hard to say for certain. Depends on the crowd. Gaming isn't quite as stereotyped to a male demographic as it used to be, but a lot of the "hardcore gamers" are still mostly socially awkward guys, who don't take girls seriously within the gaming scene. There are multiple reasons for it, but I won't get into it too much. I'll just say that it has something to do with the guys thinking girls are flirting with them by "faking" an interest in gaming, and doubt their skills with a controller. "Girl gamer" has negative connotations because most of these types of guys only perceive girls as, like, objects to hit on and they cannot conceive them actually playing video games.
But yeah high school is pretty stupid because everyone wants to be accepted by people, but their way of finding acceptance is by not accepting other people. It's a very weird social hierarchy, kind of like how a lot of people bully people in order to not get bullied.
