Comparing naxx or AQ to Tier 0.5 is not fair. The power difference in gear is astronomical, and even then 1 person out of 40 could still be pants on head retarded and get naxx gear.
A more appropriate comparison would be MC or some BWL fights and tier 0.5 as they are much closer to gear rewards power (advantage still goes to raid gear for significantly better non-generalist stats). Getting carried through MC or BWL is significantly easier and happened far more frequently than people busting their rear for a general purpose semi-epic quality set.