I feel that this is somewhat orthogonal. Yes, some questionable things have happened that made the ways how people exchange information be controlled by a handful of corporations.* But for NASA specifically, this is not relevant. They were not the ones who forced people to go to social networks; they needed to go there because this is where their audience was.

* On that note, and for the sake of the argument, I would say that the years of free uncontrolled information exchange in the Internet can probably be considered an exception. Information exchange was always controlled by governments and businesses (e.g. TV and newspapers) before, just as it is now. The fact that you or I don't like it does not change that this is how it used to be before the Internet appeared as a "free space". My generation was lucky to see how great the world with free information exchange could be, but I don't have much hope that it would stay like that for long.

I'll note that for most purposes the canonical NASA image repository is on Flickr, and it seems like NASA pays to have it ad-free for viewers.