> First, the phenomenon you're referring to is "natural monopolies" which is a well understood situation which appears in every freshman-level Economics 101 class, but that only applies to certain industries. For instance, utilities are natural monopolies because it's far more efficient to run one set of wires to every house rather than try to have 10 competing companies all run their own power lines. But most products & services don't fall into this category.
I'm not referring to natural monopolies. While I concede many of the cases people would immediately think of in my description of the early internet (Google, Facebook, et al) could readily be classified as natural monopolies, we've seen plenty of consolidation in areas that most economists wouldn't classify as such - Amazon for instance, a bookstore or e-commerce site is not a natural monopoly. And we've seen the same consolidation off the internet everywhere. There are few significant verticals, at this point, that aren't dominated by a handful of giant consolidated players. Independent of how much regulation there is or isn't in that vertical.
> Second, "free market" is a specific economic term which means markets which are free from governmental intervention in terms of price controls or subsidies, but are also free from monopolies, cartels or other anti-competitive behavior by any participant. Using the government to break up a monopoly or cartel moves the system towards a "free market". Having zero regulation which allows one or two participants to distort the market moves the system away from a "free market".
And this is where economists trip over their own feet and fall face first into the mud of religion. This is a self-referential, recursive definition that allows you to pretend a major consequence of a system is not, in fact, an issue.
You realize that you just defined a "free market" to be a market that is free of regulation, but requires regulation to maintain its state as a free market?