We discussed masteries being task/achievement based, but the reality is that it would make everyone play the game weirdly to complete your mastery track, and not doing their best to win the game I actually had the same idea as you before, but we agreed that winning would be the best for the game overall
Since most of the matches are team matches, we must encourage all the players to aim at the same goal (winning a match)
The simplicity also makes it a lot easier to understand the system and you also don’t need to keep track of all the different tasks for every brawler