I remember enchanters being able to use blur as a way of ghetto Pl'ing.

Nuke a mob down to low, blur it, let someone else kill it because the enc was now completely off the hate list.

And as everyone else has stated, that's how it's working. Moving on.

Yup, that's exactly how memblur spells should work.
50/50 chance is a far cry from never working.