i think part of the people is a classic case of "little bit of knowledge is more dangerous than no knowledge".

in this case, "experts" have been explaining to people form RPG background that historically, leather armour wasn't worn, at least not in the style that DnD used it, during the medieval period, that its become received wisdom that Leather Armour Was Not A Thing, despite growing evidence to the contrary as the internet allowed non European sources greater audiences. Now, as these sources get more known, the answer changes again, this time to Leather Armour Was Sometimes A Thing.

sort of like the samurai fanboy stage the web went though, when the pop-culture version of jap history was floating about and the European stuff hadn't made it online yet, so forums were full of posters who took the tall tales of Japanese stories and rehashed them uncritically as being accurate, and compared them to the European knights they though still had to be winched onto their horses and couldn't stand up again if they fell over. Then, better more accurate info on the real medieval Europe got shared about and the tall tales of Japanese super-samurai were picked apart and shown to be myths or exaggerations, so the pop culture consensus swung to a more neutral position.