A Democratic Democracy of course.
That...is not actually an answer, unless you mean a true democracy. Which has never worked, and is not likely to ever work. Hence why the US is a republic, and not a democracy.
Yes, and Fiat money has always failed yet people still seem to want to try it out.
What? The fiat system demonstrably works. It worked for a very long time in ancient China, it has worked multiple times throughout history, and it works now better than any other system we've found thus far in the modern era. Might as well say democracy doesn't work, because historically they've all failed in the end?
A more nuanced system is invariably worse then the current system, it takes more time, decreases your chance of success and fails to reward your Nat 20 in any meaningful way.
It might take slightly more time, but it does not inherently decrease your chance of success. At all. On the contrary, it potentially increases it. It is entirely dependent on the DC (or the target number you need to accumulate, if based on multiple rolls). It's like the difference between a 1d12 vs a 2d6. The former is a flat line of the odds of any given roll, but the latter is a bell-curve with the middle being vastly more common than the extreme highs and lows. Hence, the latter gets progressively more accurate the more towards the middle the rolls are, but more difficult at the extreme highs and lows. If you are requiring multiple rolls for a given task, you have considerably more statistical control over over whether or not the party is likely to succeed or fail, while still actually allowing them to succeed or fail. Whereas relying a single roll instead causes any given roll to be potentially extremely swingy. You can tailor every single DC of every roll to the exact 5% increment percentage chance you want them to succeed, yes, but that potentially leaves essentially nothing internally consistent, at which point you might as well just not bother with stats and tell players, "You succeed on an 11-20", "You only succeed on an 18-20", etc. Multiple rolls also allows multiple skills and/or multiple players to share the spotlight, working together to succeed. Instead of having everything constantly rest on one roll by one player.
How should a skill check reward a nat 20, anyhow? A nat 20 (or nat 1) means nothing special in a system where there is no crit success or failure (see: D&D's skill system). And if you DO reward nat 20s or punish nat 1s on skill checks above and beyond, then it has the same pitfalls discussed in another thread about why crit success/failure systems are so skewed: 1s punishes a character who is BETTER at something more than a character worse at it, and 20s reward a character who is WORSE at something more than a character better at it. A major disadvantage of using a single die for a check.
EDIT: To explain the last bit, rewarding nat 20s (or punishing nat 1s): Ricca Suave, swashbuckler extraordinaire, is amazing at diplomacy. She requires an 11-20 on a specific Charisma (Persuasion) check to succeed. She should get a natural 20 on 10% of the rolls she succeeds at, on average. So, 10% of the times she does succeed at that check, she will do so spectacularly well. Bubba Jay Foulbreath, rancid barbarian, can only succeed on that same Persuasion check on a 19-20. So a full 50% of the times that he succeeds, he does so spectacularly well. Meanwhile, Alaister Crow-Lee, aarakocra rogue, fails a Wisdom (Survival) check in the Woody Forest on a 1-10. 10% of the times he fails a Survival check, he fails spectacularly badly. Bear, the actually-a-bear druid, only fails a Survival check on a 1-2 in the Woody Forest. So a full 50% of the time she fails a Survival check, she actually fails spectacularly badly.
You are, in fact, rewarding the unskilled more spectacularly on their successes, on average, and you are punishing the extraordinarily skilled more horribly on their failures, on average. This is why a crit fail and crit success system doesn't work very well in D&D. Not in combat, and not on skills. Granted, it's generally accepted in combat, even when ridiculous: That dragon only misses you on a nat 1, so EVERY time it misses, is misses so badly something awful happens to it. Meanwhile, its goblin slave only hits you on a 20, so EVERY time it hits, it does so for critical damage; it can never do normal damage to you.
