Balancing around the average player is a terrible idea in any kind of semi competitive enviroment.
I define good thieves as the ones in my static that easily pull their weight when they play it, the average GW2 player doesnt even know what a rotation is.
I think you might not now what a strawman argument is, considering I only said that every single mAT finalist team ran at least one thief. (Also I dont play WvW)