"It's a lot easier to take over a market with no dominant incumbent than one that does"
That's why antitrust laws do exists and dominant positions are more heavily regulated.
Google, Facebook &C. have now a too big impact, they are no longer small innovative companies.
When pollution became an issue threatening people lives, it was clear that industries couldn't be let to self-regulate, because profits would have always trumped safety and health.
Google, Facebook and & C. are creating a new type of pollution, which is no less toxic.