Like another poster I see this rarely.
I don't see this tactic as cheating or bad play, it's something that's within the rules, so frustrating as it can be, work out what's bugging you here and see if it can be fixed.
I don't have a problem with someone doing it, I don't actually believe that it's any good against someone who understands what they are doing. Let's face it you will never get more armies than you would have done and will probably get a lot less. The only bit wrong with it for me is that it can extend the game to an unusual degree, so I have an alternative suggestion to deal with this for the casual (i.e. 24 hour game)
At start of game you have up to 24 hours to take a turn.
If you miss a turn then you have up to 12 hours to take a turn.
If you miss a second successive turn in a game you are flagged as absent.
Once you are flagged as absent then for that turn and any remaining missed turns in the game you have only 6 hours to take a turn.
You receive bonuses as with current rules - for whatever you would have received them.
This allows a reasonable time for real emergencies but allows for someone who stacks armies to play that way without really impacting everyone else in the game. If they are really brave they could try missing 5 turns
As long as everyone else in the game knows the consequences of what's outstanding then they can plan for it in their play.
... so there is one more refinement possible perhaps. In the missed a turn message in the log, could we not extend this to show how many armies should have been placed on the board. This will allow calculation of the risk of them being dumped near you should you attack this individual.
Comments??
