The above image is taken from the guild CnD and their benchmarks for the bosses using mirage.
This is mainly for raids, I think people have made enough discussions about pvp. So, I have just watched the shatter mirage and damage benchmarks on bosses mainly focused on stacking as much confusion as possible and the damage outcomes are not normal. As being the only class to apply such crazy amounts of confusion I think either the damage bosses take from confusion has to be nerfed or the general amount of confusion that mirages can stack.
I do play mirage but I am quite bored of playing it in places that you “must only play mirage” but as for power favoured bosses you can switch between many classes and have quite some options, but for largos, matthias or desmina there is literally no option for anyone to play other than mirage. I prefer different classes being able to be effective in some fights not a single class to dominate every other just because it can stack confusion.