This thread is TLDR but I'm going to post anyway:
I just want to say, I used and advocated this same tactic.
A) Draining is easier than filling. The natural 'draw' scenario is everyone having no money.
B) Saying that people are using this just to log off isn't a fair argument about the tactic. I used it, and advocated the use, in order to have my bounty NPCs swamp enemies while we PK'd them, instead of getting them drained offline.
C) Saying that the mechanism 'makes no sense' makes no sense. Firstly, it's a fantasy game- nothing makes sense, deal with it. Consider it in terms of game balance. Secondly, it really does make sense to order your men not to run out and get killed needlessly when you aren't there to support them.
If you want to argue against this, argue that it's unbalanced, not that it doesn't make sense or that your opponents are cowards.
When you go to make that argument, you will probably be wrong. Offline draining is already really easy, and denying players a way to mitigate that undermines an already unimpressive defensive advantage.