Say what you will about WoW, it did the "pre-raid" phase better. Since BC there's been 9+ dungeons to farm, all dropping unique loot in addition to dungeon currency, there was reputation gear, and crafting gear was actually affordable.

While there may be other methods of obtaining tomes besides CM, CM is the only one that can be reliably done quickly in the DF. AK runs are often slow or dissolve at second boss, Praetorium runs will be much slower than CM + longer queue, primals give such a pathetic amount that it's not appropriate to call it a "viable" farming method. In order to make AK/Prae farming efficient you need to form a premade which takes additional time and effort...and at the end of the day you're still running the same instance over and over.