This was the case for Naxxramas. It was Naxxramas that did this. There was a problem with gear, and then they did it again with mounts. Blizzard is known for WOW Classic TBC Gold making people feel as if they're wasting your time. But then, sub numbers decrease, and they finally fix the anti-QoL systems once the game is dead.
In reality, 9.1.5 is just 9.0 but has been fixed. The new content won't appear in the game until 9.2 instead of 9.2, which would have been 9.1. This is why many users aren't renewing their subscriptions for 9.1.5. The actual content will not be accessible until 9.2 and you will be able to actually use the fixed systems to play the game.
c. They'd be tied to character power meaning that if one stopped doing them, you'd be behind everyone else. This power can also be gained by performing heroics which means that you'll be obligatory to buy WOW TBC Gold complete them every day , even if aren't fully t6 bis.