Democracy isn't really about the people having a say. Especially not having to be correct. That's window dressing on the core advantage, which is regime change without bloodshed. Under other systems of government, prominent supporters of the old regime generally lost their lives or were exiled.

Regime change without bloodshed changes the incentives for rulers enough that it's worth them building anad preserving things rather than just extracting as much as possible for themselves and their families and supporters. There's the chance they can come back.