This wasn't the case in cata with DS, far more people were puggin normal DS decked out in LFR gear, then trying to upgrade gear from normal modes.
They lowered the chance to get LRF gear in MoP
A MoP GhostCryer video is on wow insider, He goes into detail stating that players shouldn't gear up in a few LFR runs
This is a major contributor as to why people aren't in normals