There was a thread awhile back that had snapshots through WoW’s history of the forums showing that GD has never really changed no matter what expansion. Even Wrath, BC, and Vanilla had large amounts of complaint posts.
Not diminishing any of the current ones on BfA or saying they’re wrong, but just that a lot of people don’t remember those past expansions and only focus on the current and assume the sky is falling. When the majority either likes it or is indifferent to it like Greg is saying in that tweet.
People are fondly remembering Legion now, but forget the outrage that followed Legendaries from 7.0 to 7.2. There were multiple threads a day with hundreds of replies with feedback about them.
The forums are a good gauge of activity but not necessarily the “state of the game”. That’s a little more complicated.