Without knowing what the maintenance bug they referred to was attempting to do, we may never fully understand what’s happened. Nothing I can think of, even after a great amount of thought, makes sense to me.
- This has happened to active, large guilds, and smaller/individual guilds
- This has happened to Alliance guilds and Horde guilds
- Some banks have been wiped clean, others have a portion remaining (and the size of that portion varies dramatically)
- Blizzard has said that this primarily affected profession materials from old expansions (which is my own experience – I’m missing my thousands of old-school dragonscales!!! And other stuff, but I’m still angry about the dragonscales.)
Without knowing what the maintenance was scheduled to actually do, the only link here is that banks with old profession materials were hit. However, other things were also lost, including recipes (I had hundreds that are missing), mounts, pets, etc. So perhaps we can say that if you had old profession stuff in your bank (perhaps including old recipes), your bank was a valid target for whatever the bug was. I’m not sold on this, but as far as I can tell, it’s as close to a commonality as we’ve found.
As to the theories Saturnine has surfaced:
Even if something happened to the production database, they have to have backups. To not have backups after 20 years of running this game is unthinkable. If they have no backups, they are even less capable than we think they are. But I truly don’t believe that to be the case.
Same thing as above. Standard practices mean having multiple backups in multiple locations. So if they’re using Amazon Web Services (… or maybe Azure, now that I think about it), for example, there are numerous regions. Northern Virginia and Ohio are the US East 1 and US East 2 regions. So you could easily copy data from one region to another using something like what’s described here:
https://aws.amazon.com/blogs/storage/transferring-file-data-across-aws-regions-and-accounts-using-aws-datasync/
If it were being done as “discipline”, I would imagine our accounts would be locked or I’d imagine we’d get email or in-game warnings. If they thought we were bots without a doubt, I don’t think they’d just destroy, for example, 70% of my guild bank. They’d just lock out the account until I, being a human, complained. None of my behaviour has ever been even slightly bot-like. 
As to the streamers…
This is what mystifies me the most, I think. Yes, if WoW is your bread and butter and you get your actual living income from streaming or making YouTube videos about WoW, I can see perhaps not wanting to risk anything happening to your golden goose. Or perhaps Blizz/Microsoft did warn streamers not to talk about it. Anything is possible, especially because we don’t have any information.
I think if we apply Occam’s Razor to things (the simplest explanation is usually the right one), then this is likely what happened:
- Bug happened
- No one at Blizz noticed
- Players began to notice
- It wasn’t a flood of people, but it got to be bigger as time went on
- Blizz started to look into it, by now probably a few days after that maintenance period, if not more than a week
- Blizz went
- Blizz spent a couple of weeks identifying the source of the problem and resolving it
- Blizz/Microsoft did a cost/benefit analysis and decided that the time spent to massage the data in order to make sure any remaining guild bank stuff wasn’t duplicated or that used stuff wasn’t duplicated, then actually restoring a few thousand accounts separately was not worth the time or energy (ie: money) to do so
- Blizz posted a very carefully crafted note here on Sept. 20 and mailed out a few things to some number of guild leaders (usually crap, frankly)
- Meanwhile, the streamers/YouTubers were largely unaffected or didn’t even notice they were – and if they did, they again didn’t want to risk their golden goose by making noise
Ultimately, I think that’s what happened and roughly how it went down. I would love to know more – I think all of us would! I just don’t think we ever will.
I know you were affected too, and the situation blows.
It’s the only thing that makes sense. Oh! And then - the backup db’s - also caught on fire. mm. lol ><"
I will continue to make noise as best I can. I’ll probably take a short break unless there’s, you know, news about things, but I have at least one more video up my sleeve.