Interesting point. What helped you become friends with those people in the first place? For myself it's usually a common background or shared interest in something, which for example enables us to jokingly rank the best video games, which we are all familiar with from our childhood.

Honestly it's mostly about collocation, which studies have shown to be the most powerful factor in friendship formation. My best long-running friends that I'm still in regular contact with are all people that I met freshman/sophomore year of college because we lived on the same floor in the dorms. Now obviously most of the people on my floor I didn't make friends with, but I did make friends with the ones that I got along with. And yes there's some shared interests involved as part of that, but proximity was more important. I was in the CS major and I actually didn't make a lot of friends in the major at all; we didn't gel well for whatever reason and the classroom environment wasn't suitable for getting to know people. So my college friends ended up being a diversity of majors plus a lot of landscape architecture majors, because my most outgoing friend was in that major and he made a lot of friends in the major because of the nature of it (lots of time spent together in close quarters in the studio doing project work).

So I wouldn't say I've explicitly made many if any friends over shared interests in music, but then once I had friends for whatever other reasons, we shared a lot of music with each other. Hardly any of them weren't "in" to music, and indeed some of them quite the opposite; they ended up in a band together (and I would occasionally incompetently noodle along with them on vocals/bass/guitar, but I wasn't remotely good enough to play out like they were).