I don't know about simple checks being enough to reward xp. I mean, sure, there are tables that focus on social interactions and therefore have finely tuned reward systems for that but I'd rather have it in skill challenges only. Where in the interaction you have to succeed subsequent checks to get to a desired outcome. This can be persuasion in dialogue while perceiving something fishy about the person you are talking to, then recognizing what the person is fumbling about.
On the other hand, why not. Then maybe sleight of hand pickpocketing could reward xp.
But one question remains: How would you justify (in-world) the shared xp when the pickpocket loots all the city, or when your 20 charisma performance specialist charms everyone around him.
