In the theoretical limit, a single monopoly owns and dictates everything. That's bad.

In today's mega-conglomerate market duopoly situations, these companies' cash piles and revenues are so big that they can lumber into any industry they want to, dump on the market, kill healthy incumbents, and then leave shittier products and economics in their wake. They get to use their massive "platforms" as taxation dragnets. The platforms themselves barely innovate, yet they rake in enormous revenue streams by taxing all other participants and being the central connection point for all economies.

Is it healthy that we only have two smartphone providers? That they can extort every industry - including crazy unrelated industries like fintechs, automotive, various entertainment industries, etc.?

Is it healthy that the "URL bar" now means Google search in 95% of the panes of glass humans use to access the internet? That a search for a company's products are now a competitive bidding zone where every market participant is taxed on basic branding?

Healthy capitalism should be brutally competitive. It uses regulation to ensure companies do not grow too big to escape evolutionary pressures. Google, Apple, and Amazon ought to be sweating - not sitting by the pool, relaxing. And they certainly shouldn't be able to become invasive species in other markets when their entry amounts to dumping.

I love capitalism. A healthy dose of antitrust regulation makes it more distributed and less antifragile. It makes sure lots of stakeholders can pursue lots of objectives rather than concentrated labs that are merely the lavish luxuries of titans. It prevents laziness and ossification by forcing everyone to be nimble.