the reason crabs are worth more is because they're limited.
same with dragon hes worth more, because he has a incredible re spawn timer.
when your jungler decides to be one of those junglers....that sits in the jungle and farms devourer, i suggest you do these 2 things.
Play passive! do not die. - your jungler coming out with sated while hes lanes are 0/0/0 is a good thing!
Buy ward! - Nullifying the enemy junglers attempt at ganking helps not only you not to die, but also your jungler get ahead, as he is afk farming.
i know it sucks when the jungler afk farms, but theres ways to play around with that.
stay safe. ward up, and be patient. chances are hes choosing this method of jungling because he doesn't feel confident in ganking.
maybe the enemy has way too many escapes, and he feels you guys wont get the kill or even a flash. so hes afk farming.
but do you really want a un confident jungler ganking your lane ;0, he could probably make the situation worse by dying.
atleast if hes afk farming he isn't feeding!
you just need to know how to play around having an afk farming jungler.