Why? I’ve noticed things go full circle with gigs, used to be the youngest there, eventually became the oldest, weirdly now seem to be about the average age at most things I go to. I think for these gigs the promoters should recognise their audience aren’t students who can do/want late nights all the time. As for minimal support acts, depends on the headliner, but a lot of the bands I go and see are ones I’ve liked 15+ years, it’s less likely they are gonna come up with appropriate support acts, I didn’t say no support it’s just when there are multiple.
If it is a newer band with a young audience promoters should cater for them, if it is an older crowd who would appreciate not getting home gone midnight on a weeknight then promoters should cater for them. That’s not depressing it is practical. I go to a lot of gigs but would definitely go to more if finish by 10 was the standard