botting networks for quests has been done multiple times,
making an roadnetwork for questing is already feasable, making an bot that just delivers items is childs play in comparison,
idk wich world it was, but it started with culling questgivers, untill you have an amount of good ones in the right places (moose quality over high q moose spot , dragonfly on swamp etc, ) then building roads between them, and partially blocking them,
but yea, if an mechanic cant be feasable utilized by 99% of the playerbase, and the 1% becomes untouchable simply because they can afford to abuse it, its an bad mechanic.