Good point: RTFM and (wall of slop) are two ways of telling someone that responding to them is not worth your time that are both ruder and more time-consuming than simply saying nothing. Explaining the culture of RTFM, i.e. "if there was any way you could possibly have found the answer otherwise, you should never have asked the question" to non-tech friends usually results in disbelief.

But the slop-wall is even worse, as it wastes the questioner's time in figuring out that they're just getting slop. At least RTFM is efficient.