Yes that happens - I started off being the most valuable roadie - I towed the trailer and set up the sound system (and sat in as a very tentative third chair) I am now the only one remaining of that band because musicians move on. Like the Vulgani I have evolved (a bit). What's my point here? There are many roles in a band that make you valuable, and most bands will allow you to develop musically to keep you around for the other services you may volunteer. Then you surprise them one day and they discover you have musicality too.