But you totally can intimidate (or persuade) an hostile opponent to give up the fight. Otherwise, there would be no "hostile" disadvantage to checks (there would be no check at all). "Intimidate a monster" is clearly listed in the Influence action, for instance.
Oh, it's a great use in theory.
In practice, no, I'm not going to let you frighten Orcus into giving up and begging for his (un)life because one person made a high roll and now my climactic fight is scuttled.
This isn't a problem 4e really dodged, btw. Though it limited the valid targets to being creatures you've already bloodied, I still don't think many DMs would, in practice, let you force the bloodied ancient dragon to surrender just because you made a good skill check. Talk about an anticlimax. Intimidate was arguably better in 4e (I'd argue that!), but it did have problems.
This is quite close to the same problem that "save-or-suck" / "save-or-die" spells have, and related to why holding a knife to someone's throat isn't really a reliable way to threaten them in D&D.
Which, to me, goes back to monster design and the function of combat in the game. I want a game where...
- Some (maybe most!) encounters can be ended with a good Intimidation check (or a quick Fireball or slitting someone's throat). These should still drain some resources, but don't require a lot of decision making or die rolls.
- Encounters that are meant to be climactic aren't ended in any of those ways -- they have to play out. These can be tactically rich and should definitely contain the possibility of a TPK (even if that possibility is kind of distant). They are exceptional and risky and you don't get to Hold Person the villain and then just wail on them. Characters who use encounter-ending abilities in more climactic encounters should still contribute a bit by the use of those abilities, it just shouldn't end the fight (ie: Intimidate causes Frightened status; Fireball still does damage; Hold Person might burn some HP off the monster as they resist, etc.).
D&D 5e (and 4e before it) are all type 2. D&D 3e was probably too much type 1 (5MWD and Rocket Tag originated there, after all). My AD&D experience is fractured enough that I don't trust my gut entirely, but I get the vibe that it was Type 1, but could swing against the PC's just as easily as it could swing for the PC's.
All of which is just to point out that the game isn't set up to let people make good use of the Intimidate skill. Even if the rules explicitly tell you that you can intimidate creatures into surrendering, if it's just not going to be fun, it's not going to happen in practice. Gameplay routes around rules that don't serve it (usually).