PTR's do not work. Look at Warcraft not one content patch ever goes smooth. all people do on PTR's is play with things they don't have on live servers or try to get a head start on content so that when it goes live they can blast through it. Plus the biggest problem with PTR's is people do nothing but make useless tickets or forum threads about "OMG you nerfed me" or "I think such and such should be this way or that".

In short players are stupid when it comes to what they really want, also people don't use PTR's for that they are there for just wasting Dev's time reading page after page of trash diverting their attention from matters at hand.