Something that's easy to overlook

Weekly capped tomes: Mythology(2.0) soldiery(2.2) poectics(2.4)
Unlimited tomes: Philosophy(2.0) Mythology(2.2) soldiery(2.4)

Weekly capped coil raid: first coil(2.0) second coil(2.2) final coil (2.4)
Unlimited farming coil raid: first coil(2.2) second coil(2.4 )

Crystal tower weekly loot cap: Labyrinth of the Ancients(2.1) Syrcus Tower(2.3) World of Darkness(2.5)
Unlimited crystal tower looting: Labyrinth of the Ancients(2.2) Syrcus Tower(2.4)

2.1 saw the rise of weekly capped tomes from 300 to 450. None since then

Make your own assumptions.