I fell out of the loop for a bit. Well, more of a stopped paying attention to the loop because who cares? There was some disconnect between the loop and me. No, fuck that, me and the loop. It's a fucking loop, it doesn't get the respectful "you first" grammar.
So anyway, something about an achievement for guilds and legendaries.
I turned in my cooking daily and WOOSH WOOSH ACHIEVABLES BING BLANG BOOM WOWZA! I was momentarily confused as to why a cooking quest would have caused me to make my guild legendary.
Turns out I'd finally hit honored guild rep, which I guess I needed to be able to give the achievement. That appears to be Blizzard's fix for the issue of what to do about grandfathered legendaries and preventing guild-hopping to sell the achievement.