"post-truth" doesn't mean people have decided to disregard truth, it means that factual truth is no longer a relevant factor in in the effectiveness of political arguments for many people. See Karl Rove's quote about the "reality-based" community (which may or may not be apocryphal) versus the American empire which simply creates whatever reality it likes.
It mostly means:
"Some people can't accept Trump got elected, so when e.g. criticism of him being sexist/rapist etc because of some comments back in the day is discarded, they call it a post-truth world. At the same time, it's not post-truth when the same people discard allegations of rape for Bill Clinton and his wife helping with cover up".
Or, as I'd put it:, both party voters could not give a rats arse about the truth, but the Democratic party has a better stronghold on academics, columnists, intellectuals and "hi-bro" journalists, etc., the sort of people who would just single out the others' disregard of the truth as "post-truth".
Turns out there is good money in just making up crap and printing it.
The only two things I could identify as uniquely a problem today that weren't problems in the past are A: the money is coming out of journalism faster than it can adapt to it and B: the incredibly immediate pressures to be first and get the most clicks. The latter being a thing that has always been present to some degree, since journalists have always made money by attracting eyeballs in one form or another, but the immediacy of the pressure today I'd say is a quantitative change that becomes a qualitative change by sheer size.
But I'm still unconvinced this is a new low, rather than one that we're detecting. Journalism has some nasty stuff in its history. It certainly hasn't reached a new low if you step outside of the United States. The press still hasn't quite reached Pravda lows, but I will conceded it is currently engaged in a full burn towards it.
There is no objective transcendence between facts and politics decisions.
You can believe that climate change is created by humans and still decide not to do anything about it because you also believe that technology will solve most of those problem, or that there are bigger problems (astroid hitting earth for instance) etc.
We are absolutely in a new mode of politics, one that transcends mere differences of opinion. To pretend otherwise does everyone a disservice.
"I never had sexual relations with that woman".
"Read my lips: there will be no more taxes".
"It depends on what the definition of is is".
"I will close down Guantanamo Bay".
Or don't care. Some people in the US are so far under water, they are desperate for change; such that they'd back Trump whatever.
Sexual allegations? Who cares if he can actually tries to bring back my job...
Note, I say this without any implication of whether the allegations are true. My point is, people might not care either way. A sexual predator that fixes things is better than an someone virtuous that does nothing.
The only disservice is to claim that things are somehow different when they are in fact the same.
