Except the right that believes in the traditional tenets of conservative thought is basically non existent as a political or intellectual force. It's either power grasping slimeballs like Mitch McConnell, grifters like Trump or deranged racist conspiracy freaks. The Dems are
I don't think it's non-existent, I think it's been recently overshadowed by the loudest people who make a lot of noise and headlines. A mild-mannered Mitt Romney doesn't make the headlines like a Ted Cruz does, because Cruz is an arse, and the followers of a Trump are more passionate than people who like someone like Romney, because Trump is further to the right and wants a lot more change in this culture war.
The problem I have with centrists is that too many seem to see moderation as en end to itself and so they end up standing for absolutely nothing. As for the left went too far left, as someone who has been in left circles for decades, I don't buy that at all. What's changed is the extent to which niche cultural issue shave been seized on by the right as evidence of the left going too far because the right is obsessed with a culture war they've already lost and have abandoned everything else.
Nobody can deny that the left has swung more to the left in the last 5 years or so, while the right has polarized more to the right. The right isn't the only one obsessed with a culture war. You need at least 2 opposing sides in any war. The left is struggling for one thing while the right is struggling for the opposite, and they both see themselves as victims fighting for their rights.
This all comes from demographic change of race and culture in the West and America. The white babyboomers are dying off and their children aren't having as many kids, while more immigration from non-white countries fill that population gap. There's more ethnic minorities in our society than ever before, and they're fighting for their space, while rightwing white people are fighting to maintain the space they've had since the beginning of their respective countries. Conflict of some kind was inevitable. You can't add millions of ie: Muslims to the UK or France and not expect conflict. We just have to hope that things sort themselves out eventually, and this doesn't turn into something we never get rid of like Sunni vs Shia or Quebec vs Canada.
One of the problems with the left is they can be naive and overly idealistic. They preach multiculturalism and assume everyone can get along, but reality is usually a lot messier because groups inevitably struggle for power and dominance. (I'm not saying multiculturalism is bad, I'm just saying it's messy).