My opinion on social skills is that if a character is terrible at RPing and trying to come up with a interaction for how to get a shop keeper to lower a price or to do them a favor, just have them roll the dice and tell me what theyre attempting to accomplish. for example if a character wants to distract the shop keeper, they can do this several ways
Intimidate: you hulk threateningly in the store often being overly rough with the merchandise making the owner keep his eye on you
Deceive: you rush into the store telling the shop keeper that theres been an accident and he needs to come help
Perform: you go crying into the shop and tell a sweeping story of your poor sister who just needs some medicine your not looking for a handout but maybe you could do some work round the shop.
However if your character is good roleplaying social skills then they should be roleplaying their actual characters social graces not their own but as many players who are good with words tend to not do that, i still require a check on the most compelling of arguments. it does't matter what the player says if the character fucks up the delivery. doing so requires a firm hand from the Fatemaster or dungeonmaster or any game that has a social aspect to it. when you say its this check its that check because thats what type of check your making it sound like. if the barbarian says im going go lift that boulder he has no right to complain when i ask for a strength check instead of intelligence because he was going to set up a complex system of pullies and levers to lift the boulder. I've had a few social hagglers and imo just giving into them just makes it worse as theyre always haggling for the best result.