the benefit of democracy is primarily that it prevents governments from doing bad things, less so that it empowers more effective governance

It can do either, and can fail to do either. It’s the people having power that enables the outcomes, not the system itself. Democracy just grants the power to a broader set of people.

Democracy is not about being smart or dumb.

It's about everyboty having a say in decisions of government that affects them.

The failure of democracy as a system is not when people make dumb decisions (experts and high-IQ people have made some of the most stupid and catastrophic decisions in history), but when people's collective decisions are not being respected.