Anyone who played during that time in Cata would remember that the massive amount of interlocked trash packs and Insta wipe mechanics, coupled with horror-show revamped healing drove people away in droves. Healers straight up quit pugging.
Comparing dungeons in Cata to any other expansion proves that they only read about it. It’s obvious they read that somewhere, tried to add to it, and landed with a thud because it was 100% wrong.