The relationship between the toxic work environment at Blizzard and the game’s steady decline since the end of Wrath of the Lich King are very possibly linked.
Consider that a toxic workplace scares away employees. The best employees have the best skills and therefore the best job prospects. They will leave first.
The people left will be veteran employees who subsequently put up with even more harassment. When they leave, the native knowledge pool really begins to dwindle.
By the time new hires are leaving, the games the company makes are sinking fast. The least talented people remain and they fail to hold to the original vision of the first wave (most talented / most experienced) employees at the company.
Even if you hire world-class developers, their vision of the game and the original vision are disjoint. There is no continuity between the initial plan for the game and the changes being made to the game.
This isn’t just true of video games. Look at what happened to Dungeons & Dragons after they fired Gary Gygax. The thing that resulted in Gygax’s removal from TSR (the then-holder of D&D) was his insistence that authors of TSR modules, books, and other material be allowed to retain ownership of their intellectual property (a move that’s actually quite common in publishing). The board ousted Gygax because he wanted to be fair, not toxic.
To say D&D suffered afterwards isn’t a joke. There were problems with the second edition of the game. The rules started becoming clunkier in many ways; the combat system became almost unwieldy with THAC0 and additional mechanics creating the need to do more hand calculations to determine what was needed to strike an opponent. Small things that were often left to DMs became huge issues demanding new rule books be written. Multiple supplements were released. While the price of core books dropped, the addition of so many supplements meant that D&D had gone from an expensive hobby to an expensive and expanding hobby—you needed a lot of money to buy everything and, if you didn’t and you wanted to run a campaign—the rules lawyers (players who are sticklers for the letter of the rules but not the spirit) could dogpile a DM. I spent more time arguing with these people than playing the game; this is why I quit playing D&D in the early 1990s.
So, when we look at what’s happening at Activision-Blizzard we must remember that toxicity in the workplace and poor product performance are linked. The people developing WoW at present don’t have the same vision the original creators did. Sure, those creators were lowlifes who abused their underlings, but they did have a vision. Too bad they ran off everyone who shared it.