Maybe it would be a good and wise idea to let people interested in testing actually get A/B invites instead of youtubers and streamers?
I mean... advertisement is pretty important and all but if end product is flawed people might not stick for long after initial hit.
I have seen it since MoP or even cata "testing" that at this point unless you are a streamer/youtuber your chances on getting A/B invite are pretty damn low, if not nonexistent.
Next WoW expansion ain't exactly a new thing, after all WoW has been on the market for over a decade so people that were supposed to be interested probably are and these that aren't won't exactly be after watching x/y/z vid regarding it.