Tome caps are meant to extend the life of content by placing real barriers in the way of progress. This means that to beat 8-man Savage X, players must have ilvl Y, and that will take them Z weeks to accomplish. Now couple that on top of getting 1 drop a week, possibly, it will take D weeks to truly get the "best gear" available in that content.

The reason they care at the speed of which you hit these caps is because: if you cap everything you need to do for the next 6 months in 3 weeks... they run the risk of losing 5 months of your subscription.

If they keep you around for 3-4 months, there is a very high chance that you'll stick around the full 6 because of "working towards" being ready for the next big dungeon.

That the answer you were looking for?