...Its not rare (In teamgames especially) to have "too many" units and be unable to reinforce because of it, especially if you've stolen team weapons. Is there a balance concern as to why factions can't simply tell units to "go away"?...
I honestly wonder this as well. The all units mod has the ability to recall units for a resource refund. I think transfer orders isn't a thing just like how Withdraw & Refit was removed.
However, I really don't see the issue in removing infantry for no refund at all.