It is only based on the information they are feed......just like healthcare, some info is not being given to them I would assume.
You are right but it is actually worse than that. I have sympathy (but not too much) for the CBO. They are owned and operated by our National Legislature. When they are given a request, it is not unusual for the requesting Representative or Senator to forbid consideration of anything not specifically asked for.
In this case, it MIGHT HAVE BEEN something like this, "given a steady business state, what would be the impact of this bill upon the deficit?" EVEN IF IT IS OBVIOUS that it could drive businesses into bankruptcy or offshore, the CBO is not permitted to mention this unless another congress-critter asks for it in a separate report.