That's precisely the problem with it. I'd like to read more on extremists groups and see how and why they exists, what kind of people they are, why do they think the way they do, what their fight is in our society. This is the first step to build a dialog.
However, "liking" their pages is out of question. I will not support them, I will not help them further their propaganda, their hateful rhetoric. I would like to understand them, but in no way do I want to support them.
In that sense, Facebook actively discourage dialog and openness to other ideas, because the only way to receive these ideas is also to make them more relevant than they ought to be.
There should be a way for us to navigate different bubbles, to inhabit different, neutral profiles to explore other niches of population, other ways of life within our own society. In that regard, Facebook is useless because it is not interesting for their business.
Reddit can work, but Reddit also has unpenetrable walls sometimes. However, it is already much better than Facebook or Google.