Originally Posted by
Drynix
They said that the goal is intentionally unreachable and the reward very minor for the effort. This is so people won't go full mental ham ballistic grindfest through M+ 24/7 for raid prepping or whatever. This way you just use the AP you passivly gain from doing things you enjoy, some dungeons, some WQ, some raids. And have your character progress slowly throughout the expansion. Most likely you won't even reach the max AP for 1 weapon by the end of the expansion. It was designed to be that way.
I don't think its a good reason nor design, but it is the reason blizzard made it so impossible. Entirely on purpose.