In amount it's hard to tell. Google and other big players of surveillance capitalism also collect what they can. But it does not really make it any better to have an oligopoly which has a similar huge amount of knowledge about a huge amount of the population.
> At least Facebook doesn't have an army, or paramilitaries like DHS or just about any sheriff's department I've ever encountered.
Maybe not until Zuckerberg is president of the USA ;). Also governments, esp. those who already run their own massive mass surveillance programs will use that privately collected data (at least in the long run if they do not do so already).
> The way I see it, Facebook and other social media occupy much the same position as phone companies used to, both in terms of how they facilitate interaction …
Not remotely. A far as I know they did not influence on a personal level with whom you interact, when that interaction takes place and surely not the topic of the interaction. Also Facebook today is a media company which does much more than providing infrastructure for communication of individuals.
> The thing is, if it wasn't Facebook it would be someone else.
You are aware that's probably the most lame excuse to do evil one can think of?