I don't find in the Official Rules, as AFK farming being considered as an illegal threat.
So...?

 

Org- illegal
Net- legal


On org you can sell the drops at warp shop and if people afk grind- rip economy

 

So basically its illegal to AFK grind at any grinder in ORG. it will cause too many of the mob to spawn which leads to lag and increasing in entities in which it will drop the tps (ticks per second) from 20 to 0 which will cause server lag that annoys people. Punishment depends, from a kick + warning to a Perm ban