Ultima Online (like 20 years ago now) had like 30 different skill ratings (0.0-100.0 ratings points in 1/10th increments) which you got upped when you did various activities (and even if someone else did them near you ... a 'learning' mechanism). For some like 'sword fighting' you had to face a 100 level sword skill monster to get to 100.0 skill and at that high (top end) a level you had to do it alot of repeating just to get the + 0.1 (decreasing returns was part of the system). Actions affected one or more relevant skills.
You also had a overall cap total where when reaching it, a random other skills rating would have to go down when the new one went up (which led to a funny things where people could (and did) build campfires (camping skill) next to people at the bank and within the randomness that (desired) 100.0 sword skill they had slaved to get to 100.0 would tick down as their camping skill ticked up (easy as they had minimized THAT skill in upping skills they wanted (like weapon related ones) and below 20 it ticked upo very fast.
Only several years into the game did they allow players to set a mode on each of those ~30 skill for it only to decrease or be locked or set be for advancement (they also eventually raised the total cap above 700)
Thus players had to balance within their cap to specialize in skills (like magery versus weapon fighting), and kept longtime players from simply maxing out everything.
The game had no basic experience points and you got 'better' by doing all the game activities/actions'
grinding ? yes you would grind alot still .
there also werent what we have as quests (until much later in the games history)
--------------------------------------------[size="1"]Ratings are Opinion, not Fact