It shouldn't be so binary. It's fine that they can be killed, but you simply can't /do/ anything with the unit if the opponent has an adequate offmap, and that's the issue. Conversely, if your opponent DOESN'T have an adequate offmap, the thing is practically untouchable.
Come on man, you know the point he's making isnt "It shouldn't be able to be killed", it's that the unit type may as well not exist if your opponent has certain offmap options.
Which it actually not exist that much in rank 100 that I usually played. The point is, if you don't have the tool, you are a huge disadvantage to deal with a situation. Well too bad if you just keep picking a doctrine at 0 min of the game