I don’t listen to music on the trail because I do some of my most creative thinking while riding, and having anything playing would be distracting.
With that said, I haven’t noticed the boom-box trend being a problem. On the rare occasion when I encounter another biker who is using one, I only have to hear it for a few minutes before being out of earshot so it doesn’t bother me.
If I was riding with a group and someone decided to bust out their favorite bro-country playlist, then I would have a very negative experience and make note never to invite/ride with such person in the future. But so far, mutual respect on the trails prevails in this area.
Ivan