Nothing. But, as said, a lot of (most I saw) employers are not like that and, more important, a lot of people are not like that. I was employed and the only thing I learned, even though my bosses were reasonable, was that I cannot stand that situation. I love startups, I love getting my team to the top and that top is limited by my employer (at least in short term). That makes me really not like being employed.

What's wrong with being employed is that not everyone has the benefit of a nice employer. I also have a good and reasonable employer but not everyone does.