Also bear in mind that Blizzard’s reputation completely collapsed over that time you mentioned as well, with one major incident per year. That definitely had an influence, and the fact that WoW has managed to recover is astonishing.
Absolutely, the way they did communication(basically only talked about what they wanted to talk and ignored everything else) must've been partially as a result of whatever internal turmoil was going within Blizzard.
WoW team went from only announcing things and sometime gas lighting their fans about why their decision(s) were good for the game in Shadowlands.
Then things changed and suddenly you had clearly defined roadmaps, devs being more open in interviews with content creators, being more frank about features/balance and how they felt about where they were at.
They even felt confident in sometime dropping hints and teases about things for the next patch cycle.
For basically the entirety of the first year schedule of Dragonflight, content creators and long timeplayers were having the same reaction: This degree of communication is possible? Surely I'll wake up and Blizzard is going to start fucking up major features and things, but no, the regression never happened.
Nothing bad in DF has ever been as bad as the worse features/decisions from Legion/BFA/Shadowlands.
Dragonflight was WoW's most important expansion to not fuck things up and they were able to mostly achieve it.
Recovery and growth is not over though, the 2nd most important expansion is coming up next.
The War Within is VERY important to get right, especially in terms of tone/story because it's a Part 1 of a trilogy.
If people REALLY like this expansion, they're going to be much more likely to continue on in Midnight and/or The Last Titan to see the storyline through.
The War Within is continuing with DF's core gameplay refinement, breaking down old tech barriers(cross character progression with Warbands) and adding more QoL features that player have been waiting for quite some time.
But I will say, Midnight(the expansion after) probably will need a true "You've got to play THIS" major expansion defining feature to continue that upward trajectory.
This has not been present in DF and is not there with TWW as well.
In the near future, Retail will have to perform better because I have a sneaking suspicion that Cataclysm will see a sizable regression in terms of players compared to TBC+WotLK. That would only continue on if they decide to also do the Mists of Pandaria expansion.
There's also still a big question mark as to what Blizzard will do after Season of Discovery, so many directions they can go for, but some of the ideas would require a far bigger team than the skeleton crew they currently have working on SoD.