The issues are intrinsically connected. People don't just start out e.g. going from nothing to building let's say a telecoms company. Entrepreneurship and creating businesses is a cycle of growth. For instance Bezos' first 'gig' followed a summer of work at McDonalds, which he hated. The next summer he setup a week long education camp for younger kids. He only got a dozen or so signups, but he probably made more from those signups than he did in last year's work at McDonalds. When you start making entrepreneurship difficult from the bottom up, you're going to end up with a really distorted picture of capitalism at the top since you're going to have some sort of strange bias in the companies represented.

And this is where I think corporatism excels. There are now just an immense number of rules and laws that are all increasingly esoteric even to operate quite simple businesses. And that's before you get into the countless fees and costs the government demands before you've even sold your first product. In other words when you kill off entrepreneurship and start moving away from capitalism, you invariably head towards corporatism which is itself headed much closer to feudalism than capitalism.

As for the king example, this was relating to the feudalism -> capitalism -> corporatism -> feudalism loop, not your specific suggestion. As for your suggestion, there are two big issues. The first is the same as discussed here. Capitalism and competition is a growth system. The reason e.g. Elon Musk was able to create a competitive rocket and vehicle company was because he earned hundreds of millions of dollars in another venture. No individual has any personal need for hundreds of millions of dollars, but it is strictly required if this individual wishes to engage in large scale ventures - the sort of which stand to massively improve society.

The second issue is probably the bigger point. We already have countless laws, on the order of thousands of pages, of laws relating to competition, anticompetitive behavior, restrictions on mergers and acquisitions, etc. These were all geared minimizing anti-competitive ownership. But the general rule in a corporatist society holds true. We have the FTC approve mergers between e.g. AT&T/Time Warner/Charter while rejecting mergers between far smaller companies that could eventually become the competitors for these sort of behemoths that increasingly stand above the law, and perhaps even above government.

In other words, write the laws and expect to see you and I only be able to own e.g. one tavern. But expect to see the king's friends somehow manage to own thousands. Corporatism in a nutshell.