I think you might have a different definition of "merit" than OP. "Merit" to me means how much value the company brings to society. If I'm reading correctly about your point of it being legal, to you it seems like "merit" means how much value they bring to their investors.

Social media companies becoming more consolidated and influential might be legal and good for their stakeholders but it doesn't mean it's a net positive for the rest of the world. And unfortunately, as much as so many people like to believe otherwise, being a net negative to society absolutely does not lead to a company becoming irrelevant.