That’s not accurate. We’ve been lucky that we’ve not had to go through a period under someone like a Hitler, Stalin, Pol Pot, Napoleon, or Mao, or even a semi-dictator like today’s Putin or yesterday’s Pinochet.
Several of those afflicted their tyranny on developing nations, but Hitler happened on a country that was as developed as any other. Hitler also achieved power by a semi-legal process. And while Putin hasn’t gone completely rogue (yet?), he was also lawfully elected into his positions of power.
The US is the longest standing democracy in recorded human history. The principles in the Constitution are the very foundation of that longevity. Messing with the formula will have many unintended consequences, all of them inevitably bad for us and people the world over who rely on US stability for their own.