I'm honestly surprised by all the DiK mentions. I think it's a lot simpler than that. Just look at anime; the majority of it is high schoolers doing high school stuff. Sometimes it's high school + magic. Or high school + zombies. Either way, the focal point is high school because it's an easy way to get a bunch of characters together. It's also different from a work setting because nobody is getting fired for flirting and the stakes are low for characters getting into shenanigans.
The only drawback is most high schoolers are underage and that can cause problems when it comes to using platforms like Patreon. What's the next best thing? College kids.