There is an interesting claim being made.
Apparently difference between bad and good healers in this current savage tier can be up to 6k dps, which is so much that healer dps can decide if you see enrage or skip mechanics. This also contributes with PF is struggling with dps checks while statics don't since in static healers can always coordinate to optimize resource usage to the maximum extent possible.
So despite the simple healer design and all its issues it still manages to produce huge skill variance, and the major difference being not healer trinity role performance, but something secondary - dps.