I dont really consider it as a problem by myself 
Like i have no opinion, i dont like opinions, many use them out of insecurity and not knowing.
For certain views from players it is a big thing though. The current state shows there is no sympathy for a single mastery approach.
But lets agree on that there is a potential to improve the game and deepen the skill build choices to open up more variety in builds.
Bringing in some sort of support if a player is inspired to run a single mastery build shouldnt be look down upon, instead it should be welcomed for discussion and the possibility to integrate the commen conclusion into the game by devs. Thats why we write here. To improve the game for our enjoyment.
Making Single Mastery Builds able to compete in some way would exactly do that.
Its like there is no Occultist class, cause there are only dualclasses on the player side.
I know one could make a pseudo-Occu in choosing a sec mastery and just bumping the mastery bar and some minor skills, but thats not an option i gladly take.
For me its important to still see the class name in the character screen showing as Occu and not the dualclass.
You also dress the clothes u like and not just random color ones cause u know they are still clothes.