Considering the types of games Zynga makes on Facebook, why on earth would they care whether they were buggy or not?
Taking a guess, I would say Zyngas business model is based on people discovering their games, thinking they are great, and during that initial honeymoon period perhaps spending some money on tokens to open Mafia wars crates or some such rubbish, all in a rush to level up faster. This is also the period when they will be most active about pushing the game onto their friends (to try and have a bigger Mafia or whatnot)
I would also guess that any users that remain past that honeymoon period do not spend any money on the game. They know the rules, and will level up through ingame tactics. They have also exhausted all their friends and will not sign up any new users. At this point, they are not worth diddlysquat to Zynga, except in some sort of nebulous captive audience for advertising form. (There will be exceptions of course, but this will just prove the rule)
Accepting this, if true, why would a Zynga representive really care if an existing user stays or goes? They want NEW users, the existing users are just a pain in the arse.
To attract new users, they push flashy new cities, flashy new weapons, flashy new stuff, more flashy new crap. And of course all this flashy new crap creates bugs in the existing games. They dont care. It attracts new users, and thats their focus.
I played Mafia wars for a few weeks, a few years ago. I remember how buggy it was, and I remember reading some of the threads in the forums. Full of people stating that;
“Zynga need to listen to the loyal customers. I have spent six million hours in this game, and I am a level six hundred Capo del Bono, why wont they listen to meeee? If things dont improve, I will be done with this game.”
Yeah. Think about it kiddo.