I will always advocate for systems over player skill.
I should never be able to make Int and Cha dump stats and then get to use my decades of D&D experience and social development to make up for them.
I think when D&D players talk "systems," we can switch quickly to "things like combat and skill checks!" and miss the unique kind of play found in the social pillar.
IMO, a system that supports social play shouldn't be like combat. It shouldn't be like rolling dice and adding and subtracting modifiers. Maybe some of those elements are in play, but that is not the "core mechanic" of social play.
The core mechanic of social play is player performance. I don't mean skill, I mean in like the acting sense. Talking in a funny voice. Using body language. Making in-character choices that have impact on the story being told at the table. Making your PC come alive. Participating in a shared bit of nerdy improv.
Systems in that light are systems that support the player performance. Not systems that bypass it.
I get that not every D&D player is going to be strong in that pillar, just like not every D&D player is good at combat optimization or at puzzle solving. That's OK, and one of the areas that well-designed systems can really help with, just as they do in combat (where things like "no trap options" enable different skill levels to play characters of similar power). It's OK if not everyone can contribute to every pillar with identical effectiveness. In fact, I've seen some players bounce off of D&D because of the combat focus, because those systems are so demanding and so precise!
To really drill down to the micro level, system support for performative play means empowering players to make
decisions about what their character does, and empowering DMs to solicit those decisions and to use them as the building block for how the game reacts to that decision.
Like, Alignment. It's definitely got its issues, but as a gameplay rule, it's a great
social system. It gives you a simple set of descriptors and a dynamic of how they interact. In elder editions,
race was also a bit of a social system (reaction tables!). The idea of awarding a free advantage for playing your flaw is a pretty good social system.
"Insult. DC 15 Charisma check or take 1d6 social damage" isn't as great of a social system, since it bypasses the kind of delight the social pillar adds to the game.