As for MTB, commonly seen are very wide tires on narrow clincher rims.
Going back to 1989, Trek spec 8000 with 1.9 in. width on very narrow Matrix rims. Used Kevlar bead, foldable rubber.
Wide tire on narrow rim for road is just rider preference to application road terrain and probably doesn't cause harm to a tire sidewall. Personally, I don't like the squirmy feel or handling.
Back to frame material. Is the industry cloaking poor riding modern carbon lightweights and now relying on the magic tire?
Not trying to divert the topic but just the other night out with a fast group, all but myself on modern carbon- we reached a section of road having repaired frost breaks in the asphalt. The group really backed off the pace and some complained due the harsh 'bump' 'bump'.
The bike I was riding likely averaged 8 lbs heavier, Columbus Tre-tubi steel, 32 hole rims on 23mm width tubular (funny yet on some tattered and old Vittoria). I was riding on a cloud, easily covered those miles and could have crushed the pack.