Just reading over my careworn copies of Moldvay and Mentzer and they do dedicate a fair bit of explanation to 'what to do' (as GM) when the party decides to negotiate with a favourably reactive monster instead of slaying them. Roleplay is encouraged of course, but also a detailed discussion on the mechanical use of CHA as a stat roll (or how it effects the monster's reaction roll).
Reactions can make the game much more fun than having fights. With some careful thought, a good DM can keep everyone interested and challenged by the situations that can arise.
The first decision a party must make in an encounter is to talk, fight, evade or run away, or wait and see what the monster will do.
I would think that Parley (or some iteration of a CHA based negotiation move) is
totally within the tropes of D&D (any edition). I mean you could just make them GM moves:
a revealed monster bargains for something it wants for instance, but I like giving the players moves (especially basic ones) as easily identifiable tropes within the fiction.
EDIT: Oh My. I was just scrounging through the bD&D folder, with sheaths of looseleaf, homemade dungeons and monsters that I came across one of my first characters that I played (when I was a player rather than DM!)
The wonderful illustrative potential of this character is that he was created by the rules as written, jotted down on a notebook page, lovingly laid out with ruled boxes for the stats and bonuses, attack rolls, treasure, and equipment lists... His name was Brogo Bumblefoot, the lovable halfling. In this iteration he was just level 3, with barely acceptable DEX and CON but he was particularly memorable (and the reason I selected his class as halfling) was that I had rolled a 17 for his CHA. Although never a prime attribute in bD&D, it was a useful score, and I remember (even as a young player) relishing the challenge of using what I had been given to interact with the DM's story in an exciting, unusual and (hopefully) effective way. Our DM had read and loved the section on
Dungeon Mastering as a Fine Art (p.B60) and allowed us to add our CHA bonus to any monster reaction roll if we tried to talk with it, or roll under our Stat on a d20 to negotiate terms.
This then became our operandus mundi - Brogo would be in the front with the Fighter and always extend open hands and negotiate with most monsters we came across. One of the most memorable being when the fighter had been burnt to a crisp by a rather cross red dragon, the cleric lying in a pool of their own sanctified blood and the wizard cowering behind columns at the far end of the dragon's den. Brogo stepped on up and offered the Dragon a deal, just like in tales of yore, that if he was able to best him in a duel of wits then he could walk free taking one item of treasure from the hoard. Lose and he would share the secrets of the adventurer's nearby town, and details on the magical horde the local lord has in his keep.
He had an INT of 15 and thus spoke one additional language and using my meta knowledge for the DM's love of all things draconic, went with that. After some delightful roleplay, Matt (the DM) said I had a +4 penalty as it was a difficult roll. It mattered little since I rolled a 1! (This was when lower was better), bested the dragon with my wiles and walked away with a
bag of holding!