I'm going to explain my views on this in a full. It is a lot of text, but I hope it is ok.
People don't have an innate ability to distinguish truths from lies, they need to learn this skill. Before Internet and LLMs they were relying on authorities to dictate what was truth and what was falsehoods. Those authorities included newspapers and other media, but there were also courts, government officials, politicians and others. There were no easy way to spread misinformation wide, so people were shielded from them. The system worked to some extent.
Now, however, people are swimming in an ocean of lies. They haven't magically acquired skills needed to navigate in this environment. Their own judgments about truthfulness are no better then coin flips. The results are obvious: people experience learned helplessness[1], they avoid making judgments altogether. People instead are picking some "authority" and stick to it. In USA politics, for example, there are two authorities Democrats and Republicans, so it comes to choosing your side. It allows people to avoid psychological burden of making a judgement (they are afraid of failing again). Consequently, people never feel that they were mistaken, because even if they are, it is not their fault, but the fault of an authority. At the same time they see other people who firmly believe in opposite views. Here comes "post truth world". Truth is no longer universal, you can choose any "truth" you like.
However, it is possible to avoid learned helplessness, all you need is to be better than a coin flip at predicting in advance which statements are true and which are false. You need an ability to avoid traps at least in cases when you make an effort. I make an effort when I feel it is important. Moreover in the most cases I do not need to make an effort, because all previous efforts trained my skills that works by themselves. I just see symptoms and guess, and my guessed are often correct.
I think, I need to add one more important ability to have: one needs to get rid of an irresistible urge to have an opinion. It is ok to have no opinion on some topic, to keep yourself in undecided state. Moreover it is a preferred state, if you are not 100% sure or if the topic is not important enough to you to invest time to do some research and to keep an eye on it.
In light of this I do not see the world to be "post truth". I see the most of people seeing the world as a "post truth world", but it is just their rough approximation of the world, their model of it. My model-approximation is not the real thing either, I don't know a lot of truths and keep myself undecided. Yes, I make mistaken judgements also. But the probability of my mistake goes down when I make an effort to avoid it. I feel myself in control. I don't experience learned helplessness. I know that the Truth exists and oftentimes I could reach it, if I wanted to.
So your sarcastic tone is misplaced. I know my limitations and I strive to know them more.
[1] https://en.wikipedia.org/wiki/Learned_helplessness