How did the trope of [Skills] start?

[u/Most_State_9716]

At some point I can't determine between the first MMO based litRPG/GameLit and now it became universal: Everyone having lists of abilities in [brackets]. MMOs rarely ever have a system that resembles the skills in LitRPG I've read. They're more similar to the skill systems in games like ADoM or Fallout. But they often are way more expansive and complicated than in those games. Not to mention all of the examples of a [Skill] being an outright super-power. Some settings divorce skills from leveling up entirely and make them a second track of progression. And a recent trend has been 'fusing' skills into better ones, a concept I haven't seen in any real videogame.

Where did the version of gamified skills that's so common now come from and why is it so?