In some cases it is probably the other way round, i.e. some people probably started disliking LW and EY (there are several distinct (in some cases overlapping) reasons why some people might not like LW), and only then started to scoff at any mention of rationality, because it gets associated with a thing they dislike.

If what you have in mind is other meanings of the word "rationality", e.g. what someone who hasn't even heard of LW might think when they hear this word, the explanation, of course, would be different.