Amongst the top 100 most valuable companies, not a single one is ran as a worker collective. [...] I don't know how much more of a source you need.

I didn't ask for sources that they're not a thing, I asked for sources on the reasons for that.

The current legal system doesn't do anything to prevent worker-ran companies.

I'm a startup owner (in Germany) who has looked at the possibility of making my company worker-owned. It is serious effort and comes with a lot of hurdles, tax headaches, etc., because the legal system is not generally made with that kind of company structure in mind, much less the transition into it. It is very easy to start a company with the default capitalist structure of one or a few owners/investors, it requires magnitudes more to do it the worker-owned way (and do it right). But sure tell me again how the legal system is impartial in that matter.

In the end, too many cooks spoil the broth.

That's assuming that everyone wants to have a say in everything, and that there are no good internal structures for dividing and assigning responsibility. You can still have individual people who steer the ship, who make autonomous decisions in certain areas, etc. The difference being that they're selected by their peers, rather than through a management hierarchy, and they answer to their peers, rather than their managers and/or investors.