That's certainly true. I've always though it odd that the majority of role playing games feature the supernatural or science fiction as key elements of their settings.
I think that there was an early divide in the industry...
Cutoff date of about 1983...
The TSR games (including D&D, AD&D, BX, Star Frontiers, Boot Hill, Gamma World) generally lacked social skills, but did have Charisma. Cutoff placed to exclude FASRIP Marvel.
GDW had a significant number, but their use as social skills instead of paperwork skills varied widely from group to group.
ISTR that RuneQuest (by Chaosium) had some as well; Later editions certainly do.
SPI's
Dallas was pretty much nothing but social skills. It also was a total flop.
FBI's Tunnels and Trolls lacked skill-like abilities, but had a robust system for testing Luck, which many GM's used with the other attributes. Given that some of the solos have charisma checks to influence NPCs...
Palladium's Mechanoids trilogy and Palladium FRP have an appearance attribute, and a sort-of-social attribute, but provides no means for using them in the mechanics,
and derides the use of game-stats over in-character dialogue, it's pretty clear where Siembieda falls.
Victory Games'
James Bond RPG has social skills.
FASA: STRPG has social skills. Mods for RP advised.
GDW¹, Chaosium, Victory Games, SPI: Social Skills modified by RP.
TSR, Palladium: No social skills, limited use of social attributes.
FBI, FASA, GDW¹: present but not emphasized.
We know which one was the "winner"...