It is not a good idea. If they tried something like this, players would feel they had to hurry, and most likely most people would hate it. It's not without reason that it's hard to find a game that actually introduces such a mechanic. Most players prefer to play at their own pace.
Kingmaker didn't have any "hard limit" on camping (Pathfinder's equivalent of long rest) but it was absolutely brilliant at giving you plenty of reasons to not abuse it. Well, sometimes it was brilliant, at least. Other times it was admittedly a bit of a prick.