Any class, any spec, any DPS, any tank and any healer are capable of doing an M10, but not every player can. And choosing the FOTM class is just making things worse for you and for everybody you group with.
I get it, but do you?
If you play an FOTM class you think it will give you more invites, and it probably will, but if you can’t actually perform all that it means are more groups are going to fall apart, more people are going to leave, more people are going to give up entirely on M+.
What’s actually better is if you learn to properly play your favourite, or best class you can play instead of swapping to try and get an advantage. Not only does always swapping mean you are not the best you can be, it also means when the inevitable nerfs happen you do what? You swap again?
We need a way to tell what you, the player, is capable off so you can all play your favourite spec instead of players swapping around to try and get an edge due to the class they play. A good player using a bad spec will always beat a bad player using any spec.