I guess I agree with both being a problem. Maybe the way I would put it is that once a company becomes large enough it is a lot like a government. For example, if a a few tech companies ban your speech, you effectively don’t have a useful freedom of expression. Being able to yell on a street corner is not a good substitute if you are censored online.
A government is by definition a monopoly. No company can become large enough to be like a government unless it has government backing. E.g. Walmart was feared to be becoming a monopoly by running smaller shops out of business and yet Amazon was still able to compete. Eventually someone else will outcompete both, as long as the government doesn't step in to protect them.
