The key to economic growth is not firms with many employees, it’s firms with highly productive employees. You want a system that kills off unproductive firms, so that better uses can be found for their capital and employees.
You don’t want a system that kills off highly productive firms just because they stay relatively small. As an example Renaissance Technologies was founded in 1978 and has only about 310 employees today. Yet I can assure you that the US economy would not have been better off without it.