idea of requiring specific locations for Rest
This may sound like good idea on paper ...
But what would stop us from simply returning to previous "rest point" ?
If nothing, all you "add to the game" are several minutes of walking. :-/
Is that your intention?
I mean, it was already explained, you just weren't paying attention.
Nothing would stop it. The idea is not to "stop it" (which you can't really do, unless you want a lot of people crying that the game is too hard), but to make it just inconvenient enough to discourage its abuse.
"B-but I can do it anyway, it's only few minutes of walking!". Yeah, well. Enjoy minutes of walking, then? For the most part sensible people with a good grasp about how to deal with the game combat will chose to push forward and do without some skill/spell slot ready rather than backtracking for minutes.
And and if anyone is going go ask: yes, the argument "Then what about removing even that minor inconvenience and make unlimited rest spam completely frictionless?" is stupid.
There could be other sensible design decisions to discourage, "punish" or even entirely prevent the abuse of rest spam in few ways, but realistically while they would arguably make the game even better mechanicallty, you can't win against the Icelyns of this world, who would complain about ANY sort of restriction for the sake of balance as it was a personal abuse.