I try to imagine what happens if enemies had the same rules as party members:
You fight a group of 8 goblins.
- You defeat one, a second one comes and helps to get the first one back on his feet. The other 6 attack.
- You beat the second one and also take away the 1HP of goblin one. Goblin 3 and 4 come to help No. 1 and 2 up. The other 4 attack.
- You somehow manage to beat 3 and 4 and also do 1 point of damage to 1 and 2, the other 4 help them up.
- From now on the enemies do not attack but only help each other up all the time. You try to bring all of them down to 1 HP and then finish them at once with a AoE attack. Then you attack them until all of them fail 3 death throws.
- After one hour your party rests because they used all AoE spells, you rest because your fingers hurt from pushing buttons and you decide to have the second fight tomorrow because you do not have another hour of time for playing.
Except for this to happen, Goblins would have to have infinite number of healing potions or each would have to have Healer feat and healer's kit.
Under D&D rules Help action doesn't bring characters back and ready to fight.
"A stable creature doesn’t make Death Saving Throws, even though it has 0 Hit Points, but it does remain Unconscious. The creature stops being stable, and must start making Death Saving Throws again, if it takes any damage. A stable creature that isn’t healed regains 1 hit point after 1d4 hours."
