It most definitely is. But then I never said you can do without all player social skills, just the aspect of social skills described in the post I was responding to i.e the idea that in a system without social skills it is the charisma of the player that matters.
Unlike turning on the charm, being able to articulate a basic approach to argument and conversation is not something that you can play a social character without. Not if it matters at all what gets said. (And it's also a far lower barrier to entry)
Having expertise in Persuasion but being really clueless as a player doesn't really get you very far.
"Can I roll to persuade the lord?"
"Of course you can. How are you trying to persuade him?"
"?"
This may be ok I guess if all the social scenes are pit stops between combat (but it kind of gives the lie to the idea that you can play a highly capable social character without some kind of player skill in the area, as you're not really getting that fantasy), but in any kind of game with lots of social intrigue the precise things that get said are going to matter. They have consequences and they are part of the fiction. You can't do without it.
I've played in games with really socially awkward characters who play characters with high social skills. It usually doesn't go very welll. If they don't know what approach to take, then others will just basically do all the talking through them.
Really, if making social play easier for the player who doesn't have great social capabilities of their own, the key skill is not Persuasion or Deception, it's Insight. This is because Insight or skills of a similar nature are scaffolding skills, they can give you hints. eg "He looks like he's tempted to do what you want but he seems afraid", is a hint that you might want to say something to try and bolster his courage or reassure him.