I get where you’re coming from. And I agree insofar as players aren’t directly quitting because of guild issues. Outside of a few who have, the guild issues seemingly have little direct impact on subscription numbers. However, I think its more important to look at the indirect impact. And I think it is reasonable to assume that many players have indirectly quit because of the neglect Blizzard has shown to guilds.
This is first an MMO. Without other people to play with, the game doesn’t have the same appeal, and certainly doesn’t have the same longevity. How many people have posted on the forums something to the effect of “I’m quitting because my guild fell apart, and I don’t have anyone to play with anymore?” I’ve personally seen many of these posts.
Consider then how the post might be different if there was a good system in place to support guilds. The player might have been able to find another guild rather than unsubbing. Or perhaps their guild wouldn’t have fallen apart in the first place. If this scenario is multiplied thousands of times across many different individuals, it absolutely makes a HUGE impact on sub numbers and revenue.
Things we’ve been pushing for, like a functional guild finder, management tools, and proper game support for guilds, provide a framework for the thing that makes WoW so special - interaction with other people. Provide meaningful connections, and people (on average) will have more fun, play for longer, and spend more money than they would have without those connections.
In short, players frequently don’t take the time to think about how all these things are connected. Frankly, I don’t blame other players for that. But Blizzard should take the time because it’s their job.