It's super easy to fall off either cliff, and there's piles of corpses on both ends. The only effective way we've found to mitigate that is to prioritize open dialogue between all parties and try to be willing to listen to and consider things that oppose our individual and corporate values. I don't really endorse "centrism" as a position. I think it's just an informal cop-out. You can identify with different ideas from different people, but halfway between wrong and wrong is... Still not good. As far as I can figure, people are served best when they figure out what their own values are and express them honestly, take feedback as an opportunity to learn, refine as needed, and maybe take things a bit more seriously. Decisions that seem trivial at the policy level can and do translate to people living and dying.
To some degree in the recent past we've started to limit the ability for people to speak freely and the quite radical result is what you're seeing now. Ideologues can't understand that because they're viewing the world through a frame that literally doesn't let them see it. The part of the brain that they're using to execute this reasoning is simply not equipped to identify and deal with the very real problems that they're creating.
From the doctrinal perspective real liberals and real conservatives don't like the idea of limiting speech. An open-minded (liberal) person wants a society where people can express new ideas, and a conscientious person (conservative) wants a society that's reliable. Free expression (without fear of retribution) satisfies both of those desires with a really quite small social cost (you have to hear things that you don't like). Authoritarianism fails miserably on both counts and its costs are extremely high (you are labelled, your life is systematically destroyed, and you are eventually killed).
The political left is increasingly being influenced by what's being called the SJW movement (a loaded term, but there's not really a fair term to use for that group specifically). Those are people who have been strongly influenced by ideas that encourage them to break the world into arbitrary classes of people, determine who is more or less advantaged than the other, and then they viciously assault the people who they've identified as being advantaged.
This is not a new idea by any means, and it's historically been proven to be - literally - the most efficient system of industrialized dehumanization and murder that we as a species have ever engineered. This is primarily a group of people with specific psychological traits that make them especially susceptible to the shape of the ideology being spread by influential figures who absolutely know better. They have naturally strong instincts to protect and nurture people who they identify as needing rescued - which is excellent, and we need those people - but the neurological system associated with that behavior is the exact same system that we associate with the term "mother bear". If you're a cub then maybe it's okay, but if you're some poor sap who just happens to be wandering by then that bear is probably not what you'd describe as "nurturing".
It's really dangerous to proceed this way. As the political left becomes increasingly possessed by this ideology society will continue to swing dangerously to the right and end up landing in the same pit of stupidity on the other side (where the priority is on orderliness and clear boundaries between things and your nurturing be damned). We need the left to keep the right in check and we need the right to keep the left in check; not by coercion, but by communication and consensus. The alternative is a bloodbath.
The political left - at least in the states - has been previously composed of these two semi-compatible groups and now the incompatibilities which have built up over time are causing the left to break in two, but our political systems aren't really well equipped to handle that, so we see a lot of people who are liberal identifying more with republicans than they do with democrats. I don't think that's really a good thing. It's good for the "open" left to split off from the "social justice" left, but not just to be amalgamated into the right. It creates the same kind of problem and it seems like it will ultimately lead to increased conflict, which doesn't serve any of us. This is analogous to a person whose left and right arms are at war with one another and the result is that they destroy the rest of the body. It's not a question of who is right or wrong about any issue any more, it's a question of whether or not what we're doing is going to end in nuclear fire.
I'm not entirely sure how we can proceed, but it's been taking up a lot of my thinking time lately. So far the best idea that I have is to radically improve and enforce an in-depth study of 20th century history (focusing on what went wrong and how) as a non-negotiable requirement for graduating from public school.
Possibly a deeper underlying problem is that we've been evicting the very idea of "meaning" from our social system for several decades now, and nature abhors a vacuum. If we can come to a rational consensus about what our culture is really about (those of us who aren't just trying to destroy everything), and return to our responsibility to offer our young people a meaningful place in our culture as they come of age then maybe they wouldn't be so easily attracted by authoritarian garbage.