Super Thor, Heavy Trooper, Soviet's Lasher Tank, Proto-Gharial and Lancer, the Jackal Racer with the Allied color scheme, Lunar Gehenna, all are defined in their respective missions, and not globally. What's the reason for this? Is there a hardcoded limit on how many things can be defined in the rules file? I'm asking because fanmade missions are a thing, and even in multiplayer maps could sometimes use these things. These unique units being completely restricted take away quite a bit of creative freedom.
I assume there is a techical reason and it wasn't just an arbitrary decision, but otherwise, would it be possible to have these mission-only variants of units globally defined in the future?