If you continue to dumb down the game, you will lose half your player base

[Y2K21]

Blizzard stopped reporting subscriptions during WotLK, and the player base began to decline as the expansion grew older. Everything came to a head, and exploded in Blizzards face with the release of Cataclysm.

Blizz stopped reporting subs during WoD when the game lost 50% of its playerbase due to bad game management decisions.

[Vahlnir]

Blizz stopped reporting subs during WoD when the game lost 50% of its playerbase due to bad game management decisions.

And this was before the flying debacle. They lost way more than 50% before they stopped reporting. Rough estimates around that time were around 2 million players and still dropping fast. Down from 10 million at the start of that expansion.