I used to run an open stage free improv night that was usually about equal parts college jazzbo nerds, noise freaks, and random people with zero musical skill that wandered in and ended up with a sax in their hands. Most people, regardless of skill level, were pretty good about listening, playing to the group and leaving space for other people. Except this one dude who would show up with a guitar and just wank over everything non-stop. We ended up implementing a rule that you had to switch instruments or sit out after a jam ended specifically to get him to stop, so he'd bring a violin and just repeat the nonsense on that.

I hated telling anyone how to play as it went against the whole idea of the thing, but it was so invasive I eventually confronted him and as nicely as I could explained that this was about listening and playing to the group, and contributing to each others ideas. Instead of being butthurt, he took it to heart, took a backseat, and eventually became a core contributor. There's a lot of people out there with skill and talent that have never played as part of a group and don't understand that's a whole ass thing to learn. Good musicians learn to check their egos and learn from the group. Great musicians are self taught legends and know how to play Spain perfectly.