Right now, they absolutely do discriminate on the information they feed me - most of that discrimination comes in the form of "Did the author of the information pay us?"
I shudder to think of what a world will look like, where the only things known to the public are things that their authors paid for. That'll certainly be a great improvement to the status quo.
People wring their hands over the fifty cent army, but I suppose the five-hundred-thousand-dollar-a-day political ad spend is just something we get to shrug our shoulders at.
To sum it up like that reduces both the enormity and complexity of the problem they are faced with. You say you get spammed with Trump ads; how many of those ads make claims that you could prove are irrevocably untrue? Politicians and people designing political ads are often experts at dancing in the "gray area" of truth.
I don't think it is fair to deny the fact that Facebook takes this problem very seriously, certainly beyond what would be expected from them as far as business obligations go. (I'm even saying this as someone building a product that would compete with them.)