People have been leaving the game since Vanilla. We only know how many active subscribers exist at certain points in time, we don't know how many left and how many joined/rejoined in between those points.
Sub numbers don't speak for themselves, they never did and never will. There are far too many things affecting those numbers, and "quality" is only one of them.
Either way, he, and many others, are not writing off people that constructively point out what they feel is wrong with the game.
He/we write off people who "whine", many times about things they haven't even tried out yet. People who complain for the sake of complaining, usually being dismissive, acting rude, or like they are amazing game developers that know exactly how the game "should" be. Truth is most gamers don't "really" know what they want themselves, let alone what others want.
But there isn't right and wrong. Any decision Blizz makes, every mechanic they add, remove or alter, will have supporters and complainers. But the truth is most people don't give a crap. You have all these loud complainers and supporters in the forums, but the vast majority of people will play if they like, or not if they don't. They won't check forums, they won't even give much thought about how it could have been better or what went wrong.
In the end these are all opinions, but unfounded, crude and rude opinions don't do much to help and only further harm and set the community apart, from both sides.