The logical consequence of this argument is that there is no such thing as a business practice which is illegal for a monopoly, but which is legal for a startup

The logical consequence of this argument is that there is no such thing as a business practice which is illegal for a monopoly, but which is legal for a startup. As long as you start doing it when you're small, it must be OK. I don't think that holds water. The standards should definitely get higher as you gain more market share.