The rule has been in place for many years and has worked perfectly fine. A restructured full detailed post of our rules is in the works and due to be released in the new year which details exactly how the rule works.
Typically the only way you'd figure out you are being shot from someone in their spawn is being killed by them, And thus you would know whom you are looking for. Or while you are hunting said person you are engaged by another person.
Also, as far as I know you are the only one to have brought this up in a very long time.
Also also. Not gonna change the rule because of some notorious expert UCAV pilots.