That’s not the problem I’m addressing.
This isn’t a matter of, “Oh, my character is perfect in every way, they can’t fail.”
It’s a matter of immersion being broken by the roll of a dice. Imagine if in the Lord of the Rings, Frodo tries to push Golum off into the lava at the end of the movie, rolled a 1, and went headfirst over himself instead, while Golum just crab walks out.
The immersion is the story being told, not the character I’m playing. I’ve RP’d an apprentice who could barely cast fireball, rolled nat 20s. Meanwhile the Archmage RP’ing my master was rolling all 1s and setting himself on fire. That’s beyond, “Taking it in stride,” or, “having an off day.” It’s just ridiculous.
Could you imagine Dumbledore showing up at the Ministry of Magic to duel Voldemort, tripping on his robes and knocking himself out when his head strikes the ground, and Harry just suddenly starts beating the crap out of Voldemort instead, because Voldemort’s rolling 1s like Dumbledore did, but Harry’s lucking out on 20s?
That’s my issue with an unforgiving, ‘all or nothing,’ type of d20 system. It breaks the immersion of the story being told, by having characters with experience, training, equipment, etc… at the mercy of chance. Realistically, all of that mitigates the threat of bad luck or an off day.
Which is another issue I have with the d20 system. Very rarely does it get modified, because it becomes a nightmare for DMs to keep track of everything. “Okay, Sir Reginald has the Shield of Azure Light, so he takes 2 damage less from all attacks, but he also has the Crown of Costly Power which increases damage he takes by 3 in exchange for increasing his damage dealt by as much, and he just used an attack that both harms his foe and heals himself with splash healing for allies… wait, Lady Alora has the Veil of Mercy, reducing the damage of all light-wielders by 2, and converting damage absorbed into HP, and I think Arcanist Kiron has an aura which allows for overhealing…”
There’s just no way to progress or customize, especially in large scale events. The story is lost to the mechanics.