XC bikes don’t look as cool. I swear that’s the answer. I live next to rolling flowy trails and 75% of the people i see on them are WAY over-biked, wearing full armor and full face helmets. You could easily ride a hardtail with 100mm travel on 99% of them. I have back issues so I ride a full sus XC bike. Whenever someone posts on local group chat asking for bike recommendations everyone tells them to buy 140-160mm bikes. When someone asks for shorts recommendations half the replies are some form of “just wear some old dockers and some vans shoes”.
All that to say I think a LOT of people want to LOOK badass, not RIDE badass.