This is partially the result of being taught that every opinion is valid. What was taught as a nicety (don’t dismiss other people’s opinions was the intention) has evolved into all opinions are equal.

If all opinions are equal, and we’ve reinforced that you can find anything to strengthen an opinion, then facts don’t actually matter.

But I don’t think it’s actually all that recent. History is full of people saying that facts or logic don’t matter. The Americas were “discovered” by such a phenomenon.