Yes, of course. And I didn't lost an ability to see untruths, it is just my reaction to untruths became more voluntary and conscious. And as I see the argument of the OP, he says that if you didn't learn how to step over untruths, you cannot avoid being sometimes "insufferably rude about it". Unintentionally rude, but nevertheless rude. He doesn't say that one should let untruths flourish every single time.
> it's really hard to tell whether they're taking that difference seriously.
Does it have important consequences? I personally am not bothered with it much, it doesn't hinder my ability to talk with them. I can deal with it on a case by case basis, when it becomes important.
The point is that people who make this argument will often let that implication stand. This is clear, given how the argument is phrased - and clearest of all, I would argue, when places like HN are called "toxic" or "bad/awful" in the process. And of course the distinction has consequences. Letting untruths fester can be dangerous or detrimental to the public in some cases, and this is precisely where a hardnosed "no BS" attitude is most helpful.
But, but... but ¡¿¡¿por qué no los dos?!?! You can be concerned about people, and even learn to let harmless and irrelevant untruths slide, without in any way diminishing your concern for things that might actually have important consequences. When I see people like the OP advocating for HN users to be less analytical or less critical about things (and there are many of them in places like Twitter), it's really hard to tell whether they're taking that difference seriously.