I know if I were a Blizz employee, I'd definitely do it.
1. You get free feedback from
jedi scum all kind of current and past players (most of them being slightly toxic and negative ofc, otherwise this wouldn't be WoW but any other game)
2. You get to mess with them and lead them down the wrong trail. And when you're "in the know" that's a lot of fun (imo at least)
It's a win-win, you get feedback from some part of the community that aren't on official forums AND you get to protect the secrecy of the next expansion by blurring lines and throwing false leaks.