The description presented for corporatism is partial in this article. Corporatism doesn't prevent free market. In fact it doesn't care about free market. It's an organisation for the people of the field to organise themselves.

It's used since the middle ages at least. It is indeed often used by the central government to get some controle on the field (to prevent a technology from going in an enemy kingdom for example, at a time when patent didn't exist).

It is not free market in the sense that someone can't come into the business without the corporation allowance first. But many markets are just as bad anyway ; when companies have a monopoly or close enough from it, it's arguably even worse.