Don't think it's completely an age thing.
I'm 31. In good health.
No issues carrying weight, but if i have the option not to, why would i?
My lightweight rig is as good as anything else i've played through.
If you want to analyse it, i'm sure some people would say it isn't "because x or y" , but to almost everyone else, in a gig situation, it does a cracking job. Weighs less than 10kg.
So i just don't need to have heavy gear.