Uh, no.
Unless Ive missed a major overhaul in the way quests work since version 19, the entirety of the ranger questline, up to the point where you get the permanent boost increase can be done with 0 depravity, provided you take the solutions that dont pimp you out to wild animals.
Im not sure what the monastery is - if its the cult of fertility, that one offers a clearly distinct defiance vs depravity path.
For the skilltree: do you need to have the 4 skills before you can get the signature one, which is awarded after finishing a questline? As in, have animal empathy without depravity points.
As an aside - is there an updated version of the walkthrough?