I've noticed that the vast majority of people who latch onto one side of the extreme or the other are also extremely ignorant about the overall issues that they protest for or against. They can't seem to articulate their anger without chanting empty slogans.
That's what happens when people let their emotions dictate their actions.
It seems to me that this is the case for the vast majority of people in general, because politics just aren't their top priority, so they just 'go with the flow'. In my experience, Facebook definitely reinforces political echo chambers. It's a subtle, modern form of local brainwashing that leads to the creation of opinion bubbles in which everyone not only agrees with the others, but is also convinced that people who think differently are idiots or lunatics. This leads to a strong 'Us VS Them' mentality.
It seems obvious that one should be knowledgeable about a political party before supporting it, but the truth is that this is usually too much to ask. I believe this is an inherent flaw of party systems, because it leads to blind support of candidates you know next to nothing about, save for their political affiliation. How is the well-meaning average Joe supposed to make an informed choice? He is not going to sift through newspapers and books to figure out whether $current_candidate is the right leader for his country.
What I think will happen is that Joe will mostly base his decision upon his personal biases, hearsay, the looks of the candidate, and Joe's favorite news source, which will itself be aligned with his biases. This is how we end up with two sides shouting at each other without even really knowing much about their candidate.