In the late 1970's, Metagaming Concept's The Fantasy Trip was briefly in the hunt as a competitor to TSR's Dungeons and Dragons.
The Fantasy Trip, comprised of the Melee and Wizard microgames, was developed by Steve Jackson, when he was still a fresh-faced game developer working for Howard Thompson at Metagaming. Steve went on to develop Metagaming's advanced version of The Fantasy Trip: In The Labyrinth, Advanced Melee and Advanced Wizard.
While Melee and Wizard started out as straight-up arena combat simulations, the Fantasy Trip franchise morphed into a role-playing game as additional products were added to the line. By the time In The Labyrinth was published, in 1980, experience points and leveling up had become the standard approach to fantasy role-playing character improvement, and appeared in this game. But while D&D was strongly class-oriented, The Fantasy Trip was among the earliest of the skill-based systems.
Experience Awards in The Fantasy Trip were doled out for a host of activities. Here is what Steve Jackson had to say about experience.
"The record sheet is also the place where you keep track of experience points. The GM will award (or subtract) experience points as you play; they are your character's reward for staying in character and achieving his objectives, whatever they are.
The object of this game is the same as that of life itself -- to survive and to better yourself at your chosen pursuits. Experience points are awarded by the Game Master whenever a character does something "well." Any action which would teach the character something (or which shows that he's learned his lessons well) should be worth experience points. Trying a valiant action and failing should also be worth something.
Experience should be awarded as follows:
FOR COMBAT: One experience point for every hit of damage you put on a foe... [and] the person dealing the killing blow to any enemy gets experience points equal to the foe's basic Dex.
FOR CASTING SPELLS: A Character gets one [experience point] for each point of strength expended in trying to cast a spell in a pressure situation. Spells cast in creation of magic items are a special case. Give a wizard 20 xp for each week he spends creating magical items.
FOR DIE ROLLS: Making a saving throw against danger (thus avoiding it) or putting one of your talents to good use (thus learning more) are worth experience. Any character who successfully makes any roll on 4 or more dice will get experience points: 10 for a 4 die roll, 20 for a 5 die roll, and 30 for a 6 die roll.
FOR TIME SPENT IN PLAY: Each hour of real time spent in play is worth 5 experience points to each character actively involved. The GM should not award points to characters who don't participate or who waste time deliberately.
GAME MASTER'S DISCRETION: The Game Master can give out extra experience points (or take them away) whenever he feels it proper. The GM might give out extra experience points to a character who figured out a riddle, defeated or frightened enemies by a cute trick, or even cheated the other players out of treasure. Points should be taken away for actions that are very out-of-character, or for very stupid actions...." (In The Labyrinth, page 10)
Considering that The Fantasy Trip was a skills-based role-playing game, experience awards for making die-rolls makes a certain amount of sense. After all, the player selected the skill, out of a myriad of choices, and then had the wherewithal to use that skill during the game (hopefully in an unexpected and novel way).