The market isn't going to do what we want, so we're going to implement it using centralized power instead.
I didn't elect these big companies to censor the public discourse, and it's highly disturbing that they're working hand in hand with the government to do this.
Note that none of this logic depends on normative judgments
The "logic" depends on the normative judgement that what would result from a free market would be bad. There have been too few big players doing too much meddling and manipulation of the markets contained within their walled gardens to know whether that would be the case or not.