>>96407119
I really like how GURPS doesn't just have a generic social stat and that's it. You have over a dozen different ways in terms of game mechanics to define precisely why people like you or are willing to go along with what you say. And each method has slightly different rules for how they apply depending on the situation.
Before you make any skill check or any attributes come into play, NPCs first make a Reaction roll to decide their attitude, modified by traits such as Appearance, Charisma, Rank, Reputation, Social Regard, Status, and so on. Many of these traits come in multiple levels and different versions, depending on how precisely you want to define your social advantage.
Only after that do Influence skills (Fast-Talk, Diplomacy, Intimidation, Savoir-Faire, Streetwise, Sex Appeal) and attributes (Intelligence vs. Willpower) come into play, and only if you choose to roll. If you try using a skill other than Diplomacy (which is a Hard skill) and your skill is lower than the NPC's Will, then you might just make things worse.
Most of the games I run don't feature lots of social engineering, so I just tell my players to not sweat the details. But it's still nice to have these option. In games without much social interaction, I can just refund everyone's points. As opposed to some other games, where you might invest heavily into a social-heavy class or archetype, but if the GM half-asses or straight up ignores the rules for social interaction, then you're just kind of fucked.