One thing to add: in some sense, this is about how much a musician chooses to have their own site be part of a specifically online music “scene.” So, there are at least three things keeping musicians away from developing their own sites in this way:
1. they’re already part of an offline music scene, and that’s where their social linking happens
2. they’re part of an online music scene on some kind of community website, and that’s where their social linking happens
3. they’re loners / outsiders doing things on their own, and who eschew social linking
With the varied landscape of offline and online scenes, some musicians are wrestling with all of the above.
Obviously, musicians have particularly nuanced kinds of “social” links that aren’t just about friending, e.g., we have collaborators, teachers, band mates, fans, and friends, etc. And, I think the real challenge may be: is it worth the effort to try to have one’s site / blog represent the richness of all of that, or is it just a distraction from where the real action lies?