OP, We can notice this better when a new patch is released.

The people who play everyday and are used to doing things the way they should be will enter the new dungeons using their skills properly, beat them and then they will move to harder content. You will see them in the expert dungeons once in a while, but they will be in endgame most of the time.

As the time goes by, more people unlock the expert dungeons and do the content undergeared. Nothing wrong with it, you just need some extra effort and everything should be ok.

Then a strange phenomenon happens: random people who doesn't know anything about their jobs and surprisingly managed to get the requirements and people who main other roles start coming to the expert dungeons. Then you have to deal with a bunch of people who barely know what they're doing...
When DPS don't use their CDs you may or may not notice, but if a tank doesn't use his CDs, for you as a healer, it will be huge.

I guess there's no solving for this problem other than try and help people doing their best. And healers are the best people to do it, since they have in their personalities the will to help people...