If you break up the big players and all the roaches scurry to smaller corners .... the less effective they become.

The fact that there are big corporations controlling information and allowing disinformation to flourish means that bad actors have a large base to work from. And the company has all the incentive to make money on it. Literally Facebook is short selling democratic society by investing in fascist and authoritarian ideology.

Having big corporate social media companies doesn't round up and control bad actors ... they give bad actors a platform and a very large blow horn to reach as many people as possible.