When powerful call all the shots it shifts wealth dramatically towards the elite and away from the public reducing quality of life and innovation.

It would also mean any friends and family of powerful would hold the keys to major industry sectors and companies and wouldn't let anyone new in. So encumbents can never be overthrown by a new business (blockbusters -> Netflix)

This is exactly what Russia is - Putin holds all the power and whenever new company comes up who does things in innovative way forcing incumbents out - like Yandex, Vk, Tinkoff and many others - he'd either buy them out for cheap (Yandex) or if it's not successful, threaten, publicly defame on state TV and force CEO out of the country, forcing him to sell for pennies (Vk, tinkoff). All of these companies belong to Putin friends via one or another scheme.

And when you look at the map and export data by country and you wonder how despite such a massive stream of wealth from oil and gas, yet Russian people have the worst quality of life in Europe (tied with Ukraine and Belarus). Many countries have nothing and yet hold significantly better quality of life (Estonia, Singapore, etc)

Basically if you look at a country where some guy/girl who was nobody was allowed to force a powerful corporation out through their innovation and ingenuity - that's a good sign that democracy is working there.

Of course it's not black and white it's a spectrum. If we look at any society decades and hundreds of years ago, their best societies would look far worse than most today, and their worse society would be far worse than north Korea today.

Still it's obvious that more democracy means more progress and, faster innovation, better quality of life and reduced power of the wealthy.