The short answer is no.
I don't like the idea of ​​being able to save only when you rest, but let's leave it for now.

How would this work for you? Was the checkpoint disposable? If so, what would you do if the fight went wrong?
The simple answer is that the player will end up being blocked unless the game has been specially designed so that the clashes are trivial.
If they are not disposable, what will prevent the player from going back and resting?
Is the solution to respawning enemies like in dark souls?
Ok, this is a solution, but it doesn't fit narrative-based role-playing games at all.
One more question, how densely should they be distributed? Different classes have different rest requirements. In the case of DM, he can properly distribute the number of rests or the number of fights and opponents so that the group is able to cope.
We do not have DM in the game, which means that all fights will be identical for each group.
Groups can have very different compositions, which means that they can do differently in the game. Of course, you can say that the player can adjust the group as needed, but what about the coop? When 4 people are playing, they cannot change the team.
A simple example, one player has a cleric who can heal the team between fights and the other player plays without him (technically in 5e nothing prevents you from playing without cleric).
One group will need to rest more often than the other because of the damage they take.
Normally the DM would adjust the number of encounters and rests to suit the team, because after all, how many DMs are actively trying to kill players?

Now let's go back to saving while resting (unless you meant something else).
Of course, I can't say that this approach doesn't work for games, because in fact many games use this system.
The problem is that the game is 90% dice based, wrong throws can easily kill your team in no time, which will require you to load the game. As I mentioned before, you don't even have to lose, it's enough to end up in a situation where you can't beat the next fight.