Sure they would. The companies would just have to have different ownership models that incentivized more distributed ownership between more people. If we somehow said that no one could own more than $100 million of a company, then for every person who has $1 billion of a company now, there would be 10 people with $100 million instead. This would be a net benefit to society.
They would be the same 10 people all owning shares of each other's companies if you said one person couldn't own more than x of a company.
Where do all these other people who have the money to own all these shares come from? If they existed they'd be buying the shares right now, and probably own them. You hand wave that this would be a net benefit to society but don't say how, or even demonstrate an understanding of how any of this works.
This is all a misunderstanding of power, where it lies, how it works. We imagine the government has power and we can democratically change the fabric of reality, will our desire into existence with no blowback or fallout. The people that own these companies, they cannot be stopped. They exist because they have to exist, they emerge naturally. Someone always holds all the cards. If you try to pass laws to stop it they'll just hide it from you and do it anyway.
