I played Magic briefly as a teen and the thing that bothered me the most was how mana worked and the tendency to either get mana flooded or mana screwed. I even played a custom format with friends where you separated your deck and your mana into two decks and drew one from each every turn. It made the game much more enjoyable and consistent.
This game mechanic (mana burn) was removed when the rules were refactored across the past 20 years. Mana (edit:) simply disappears at the end of each stage.
Mana Burn is gone, yes, in terms of doing damage, but players' mana pools still empty after each phase.