Also… you could just add grain via post processing?
Its actually a reasonable technique, as it softens diffusion blocking artifacts the same way it softens video codec blocking artifacts.
The YouTuber sorta kinda has a point, depending on the context. Spammers tend to use the absolute laziest lowest common denomenator, so its quite possible theyre largely using the same model, with the same artifacts, and not bothering to edit output. So maybe they did have a common noise pattern? Though the way thats presented still sounds fishy to me.