Capitalism is an economic system that works best in a free market without monopolies. I believe the word you're looking for is corporatism, where huge companies have subsumed the role of government (e.g. controlling speech).
The way you break a network effect is adversarial interoperability. You build a new (ideally open) network by bootstrapping from the old one. But companies use the DMCA and CFAA and other laws to stop competitors from doing that, so it doesn't happen.