Aside from local or national salespersons, I think they appeal to folks that like to tinker. I understand there are shops that specialize in builds, but I'm aware of many that're respectable bolt rifle level tack drivers built with off the shelf parts.

I noticed AR 10's and 15's increasingly in ranch trucks. They must instill enough confidence to bounce around on a rack year round and perform on demand. So far, I don't even have thoughts of dabbling in that area.