It's important to explain your reasoning because there's a difference between just making something up(like anti-vaxxers, for example), and basing an opinion on actual observable or provable information.
In the case of flying/no-flying, we have a pretty good idea of how that went down. I get that you disagree, based on the notion that no one can ever know what goes on inside Blizzard's decision-making process, but I look at it similar to a black hole. You can't actually see a black hole, but you can make a pretty god damn good guess at it by the effects it has on the things around it.
To apply this analogy: Ion announces Pathfinder's return for Shadowlands. The most hardcore Blizzard fans(those who pay to travel to and attend Blizzcon) were heard to boo it. Is this a perfect representation of how Pathfinder and no-flying is received across all players? Of course not. Does it tell us anything about how Blizzard decides to stick with pathfinder in Shadowlands? No. But when you add it into the entire history of various reactions to no-flying over the years, it creates a pattern that can be used to make judgement calls on.
How this applies to WoD and the 180 on "No flying ever again": If you had been paying close attention to the topic, you would know that there was a pretty steady stream of negative feedback and criticism directed at the concept of wow without flying, as early as beta. Blizzard went ahead with it anyway, and the general perception after launch was mediocre. Or rather there was no strong feeling one way or another.
But due to Blizzard's poor communication, many people did NOT have a strong reaction based on the assumption that flight would return in 6.1. This had the effect of suppressing outcry, not eliminating it. When the final announcement fully clarified that flying would not be returning ever again, all of the outrage, that had previously been damped down, flared up again stronger than before. This was compounded by anger from players who had paid extra money for the collectors edition and/or cash shop flying mounts.
Throw all of that anger on top of an already weak expansion that a lot of people were angry with for other reasons, and you get the effect of Blizzard having to do something to help mitigate the reaction. Very likely this was heavily influenced not only by a rash of unsubs, but also refund requests for cash shop and collector's edition flying mounts. Pathfinder and the return of flight was one of those things Blizzard did, most likely to stem the loss.
The problem here is that this often gets misconstrued, or misrepresented(by both sides of the argument) as "Flying was why people unsubbed in WoD", or "All the unsubs were what caused Flying to be put back". When in truth it wasn't JUST about that. It was maybe the largest issue in WoD at the time, but it was exacerbated by an entire array of problems with WoD.
You may not think any of this has any value. Hell, you might ignore that any of it happened at all. But again, this is why I asked you to explain your reasoning. Because while I can't actually see the black hole inside Blizzard's decision making process, I can see the effects and responses of the players, the Community Managers, and the Dev interviews. And based on that, I can get a pretty good idea of how things went down.
What I observed happening seems to be VERY LIKELY. And it's supported by the behavior of Activision-Blizzard's actions as a corporation in other areas. Maybe I'm wrong and there's some other bizarre explanation. But at least I'm basing my opinion on actual observed occurrences and behavior instead of just making something up out of thin air based on feelings.