I do want to nitpick on “unregulated free markets”. Because it’s almost an oxymoron. At least if one wants to rely on the theorems that prove free markets are best.
Those theorems assume a bit more than just a lack of regulation. They assume no information imbalance between parties. No ways outside of competition to keep out market entrants, and no collusion between market parties. All of those assumptions, in order to approach them in the real world, really require some strong regulation.
Hence I would argue that the problem isn’t just the growth curve flattening, but also a US (and EU) halt to Trust busting. Massive weakening of consumer protection agencies, and a general weakening of regulatory agencies by e.g. court cases.
It’s not just that we need stronger regulation because tech companies reached a point in their lifecycle where they wish to exploit more, as you so clearly argued. On top of that, regulatory power has been pulled back.