I don't know when you last skied Monarch, but you can't just willy nilly drive up on a weekend in prime ski season and expect a parking spot anymore; let alone a legit 6in+ powder day.
I haven't skied Monarch since the pandemic. But I was responding to someone who proclaim Monarch isn't a good substitute for those mountains in the mega pass. In that proclamation, Steamboat was also mentioned. So I took it to mean terrain/size, not distance from population center.
Also, in the context of this thread, A-basin is in very much the same situation as Monarch. Limited parking but fairly good lift capacity and crowd free slopes. So there's not much reason to pass by A-basin to go to Monarch. But there's plenty of reason to bypass Keystone/Breck to go to Monarch/Loveland.
Your point is valid in that Monarch is outside of day tripping distance from Denver. But that's a Colorado specific situation. While that situation is repeated in some part of northeast also, it's by no means universal. My point being, the crowding hasn't reached the point that would drive people to less crowded mountains. Not for most people anyway. People don't seem to mind the long lift lines and crowded slopes. (it drove me to less crowded mountains, but I'm glad the majority isn't doing the same and making the "less crowded" mountains equally crowded)
There will come a point, when the population had increased so much that there simply isn't enough place for them to ski. But that point isn't here yet. Judging from the lopsided number of people who ski in crowded mountains over the less crowded ones. Instead, there's pressure to find parking (A-basin/Loveland/Monarch) and road capacity (I-70, Cottonwood Canyon). One may even suspect that some ski area managements are using parking as a capacity throttle to limit the number of people on the hill. But if not, then there's even stronger preference for people to want to ski in those mountains for the better skiing experience.