These comments made me wonder why the democratic principle is never used in corporations. Is it a flawed principle?
It is used in some corporations.
Labor coops are usually corporations. So are labor unions. So are consumer coops, which also apply the democratic principle with a different constituency.
One reason is that it's much easier to capture entrepreneurial rents for a capital-managed firm. A capitalist with a grand plan can hire a lot of workers and realize his plan. In a labor coop, a majority has to agree that the plan is sound - and if it's a first-mover thing, it's hard to keep some workers from starting their own business and getting there first. Dow gives some other reasons too.
Labor coops do exist, but they're usually not startups, and some types of business are much more common than others.
The Mondragon [1] corporation organizations around these lines.
In general - as I understand it - you could view Unions and Coops as attempts to apply democratic processes to operating a business.
[0] - https://www.amazon.com/Democracy-at-Work-Cure-Capitalism/dp/...
[1] - https://www.mondragon-corporation.com/en/about-us/
EDIT: for clarity and link organization
Although these days the lines seems to be blurring into democracy since corporations are getting larger horizontally and vertically.