So have I got the wrong end of the stick here then, steel frames aren’t really any different
My original 456-evo had a 27.2mm seat post, a traditional 1 & 1/8 head tube, a 135mm back end and thin chain and seat stays….it has a compliance to it that is hard to describe, I suspect they could build a carbon one with the same characteristics if they wanted to, I have a carbon fishing rod that can be bent so the top comes round and touches the handle!….incredible material but in MTBing at the moment it’s being used as a ‘stiffest is best’ material.
My current Ragley (steel) has a 44mm head tube to take tapered forks, a 31.6mm seat tube for all dropper posts out there and much larger diameter stays, top tubes and down tubes than the 456 it replaced….they are like night and day.
If I was building a ‘hardcore hardtail’ now i’d probably get a Dartmoor Hornet and go for a lighter build than I’ve ever had on a HT….or accept the ride can be harsh and buy my dream machine PP Shan!