Is it really the case? Or is it a perception you have? I've become less and less liberal the past three months, for multiple reasons, and at least in my liberal bubble, i did not face any backlash.
The other day on Twitter when the couple pointing guns at the protesters in Kentucky issue was trending, someone posited "I wonder what happens to people who don't have guns". So I posted a video of a couple who were dragged out of their shop and beaten, on video, and their shop destroyed.
I posted no words, no commentary, simply linked the video that is a real example of the answer to that question - and got called a racist in response.
People are actively seeking reasons to hate, these days, and for someone like me for whom the entire exercise seems silly, all I can do is sit back and stop participating.
Pretty hard to answer that question in HN with anything other than another anecdote, but I would personally answer that question with "yes". I have seen this behavior on several online forums I am in (including HN) as well as in real-world settings.
The well-documented incidents with "non-left" speakers on college campuses is another data point. Take a look at the insanity that happened at Evergreen College, for example.
This sort of behavior is easily observed, from my point of view, in real-life and online.
A lot of people are becoming less liberal - your liberal bubble might be trending in the same direction.
As to who gets labeled what for which action is a big mess, but the direction seems to be that people are very quick to call everyone else bad if they are not as far-whatever as they are. (Anyone trying to gather and assess data about anything like "race", police brutality, homicides, guns, socioeconomic status is instantly suspect. But also it's very clear that a lot of people just post incoherent unfounded stuff on twitter which happens to have citations and graphs and even some structure resembling a paper -- and of course discussing it on twitter is neigh impossible, but almost always an exercise in mental self-harm.)
Sadly the real internet hate machine is not 4chan's /b/, but serious platform like facebook and twitter, where real people grind their ideas on each other until they just become sharp sticks and slurs to poke others with.
However, in day to day life, there's a good chance no one will care about your political leanings, unless you live in Portland or something.