That's not true.Even then, half the raid was AFK
MC had some fight that people just coudn't do shit, and others that only required sheer numbers to beat them (if we have X healing+Y resists+Zdps, we can do it, so all other players that are not needed to reach that numbers "can" stay afk).
But you are talking about vanilla? So AQ40, BWL, Zul'Gurub, Naxx...yeah, alot of people did all this raids being afk...
I can say that I saw more ppl being afk in LFR than vanilla raids.