I fuckin hate this notion in modern dnd (which is a misconception in the first place) that its just “let a d20 decide: the game”. That’s not how the game has ever been played. If you wanna have goofy mad-lib games with your friends where you just roll dice and laugh that’s fine but you’ve never, in 50 years, had to roll to see if you’re able to cast Cure Wounds or Heal.
That is a mechanic in some other games where spellcasting isn’t a guaranteed thing. But not in core Dungeons and Dragons.