I don't have a good answer but I believe that it certainly cannot be everybody.

Perhaps people who are accomplished scholars in political theory and economics and a few other relevant areas?

Ah, but who chooses the experts? Whoever gets to do that has the real power. And I don't trust anybody with that level of power - you've given them the right to control the government, and call it "scientific", so that they can dismiss out of hand any arguments or complaints.

I don't like dictatorships, no matter who the dictator is. Spare us the dictatorship of the whoever chooses the "experts".

Dictatorships/oligarchies work very well when you have a good dictator. They work horrifically bad when you have a bad dictator.

Conversely, "democracies" work pretty ok when the people leading are doing a good job, and they work sort of bad when the people leading are sucky.

The difference being, democracy spreads out decision making to effectively limit risk.

Think of it like an investment. You can put all of your money on one really volatile stock. Maybe it will do really great! But maybe you will lose 95% of your money in an hour. Or, you can put it in a basket of carefullly-chosen stocks that have the collective goal of a slow, steady climb in value while limiting volatility.

Different goals.

Economists are famous for repeatedly making predictions that turn out to be hugely wrong, groupthink and massive political biases. Don't think so somehow.

As for scholars in political theory, laughable. What does an ivory tower academic know about what people want or need? Marx spent his entire life reading books and writing political theory and his ideas lead to disaster everywhere.

Nope. Allowing anyone to take part is a great system.

I absolutely agree that rule by ideologue is terrible. I'm not sure I agree that universal suffrage democracy is a good method of preventing ideological theocracy. How many of those voters are under the spell of charismatic ideological propagandists?

Can you offer specific examples that make you believe that the cumulative opinion of scholars are going to be objectively worse than the cumulative opinion of everyone?

Communism was essentially dictatorship of political theorists. People like Lenin, Marx, Trotsky and even Stalin had all written books on political theory. It led to mass starvation, dystopia and economic collapse.

The USA went with cumulative opinion of everyone (democracies, markets).

Which country is the world's remaining superpower?

Both the US and China are superpowers. One sort of capitalist/representative, one sort of communist/oligarchical.

Maybe it just means that extremes don't really work that well.

Does Sales Tax count? What about gasoline taxes?

Of course, they are taxes. Also the weighting need not be linear - it could be a log scale.