Venice was run by very old men. It was common for the Doge to be in their 80s. Meanwhile, many of their neighbors had kings who were very young, sometimes teenage boys.
Venice was the longest lasting, most stable state in Europe.
They took the full council, selected a random subset, had that group choose another group from the full council by voting, then repeat that random selection followed by voting another few times ending with a final group who voted to select a Doge.
https://medium.com/psyc-406-2015/how-fast-does-iq-decline-ca...
But you may be right. Maybe what the US really needs is a lagoon.
But those kings were (legally) absolute monarchs, while Venice was (somewhat) a republic. This isn't a trivial distinction. The young kings of the various Carolignian successors also tended to inherit their titles when their fathers were killed, while Venice occupied a highly defensible geographic location (a swamp) which supported institutional continuity.
Contrast that to now, where an 80 year old in his twenties likely did not even have colour TV.