Not sure “liberals” is the right word, because it kind of encompasses all of the left, of which liberals are more center than left.

Anyway…

Because it’s at odds with with our moral compass and our knowledge of how human psychology works. We believe in people’s ability to learn, change, adapt, and become a better person. We see it practiced better in Europe than America, at least very often in respect to the criminal justice system, which the American version is abusive, unhelpful, and, well, conservative. On the other hand, the left thinks that even the conservatives that hate us deserve at least a bare opportunity at education and redemption. (Or at least most of the left anyway, tankies notwithstanding, of course.) We have science that supports compassion and conversion works better than abuse and ostracism. It takes a lot of fucking time and effort. A lot more than many would say they’re worth, and I get that, but it doesn’t mean it’s impossible.

We don’t hate them the same way because we’re not in a brainwashed cult like they are. While a lot of them may be too far gone, not all of them are, and as things spin out of control in the conservative world, increasing numbers of them are starting to question what they’re backing. It’s part of why the crowds protesting for Trump have slowly dwindled to pathetic numbers and have gotten increasingly strange and unhinged. Only the true believers are left, and their numbers are already dwindling in terms of those willing to come out and risk it for Trump.

Even when understanding the Paradox of Tolerance, you’d be hard pressed to find large numbers of leftists who think the best solution is the same kind of senseless eradication of the enemy that conservatives want. You’d find a large number of them who increasingly want to be armed and prepared if they are attacked by violent conservatives, but far fewer that want to be the one to fire the first shot in such a war.