Its a bit like saying the 2nd Amendment doesnt work because you have a gun in your drawer. But if you are threatened and get it out and blow away the scumbag climbing in your window , it works great.
If it doesnt work now, Make it work.
Dont just sit on your hands and hope no one attacks. with all the third world butt wipes trying to get Nukes and missiles now , we better find something that works.
SDI may or may not have worked in 1983. The computer technology available then made it iffy. That is not the case now, processor speed makes accurately targeting a missile possible. Liberal opposition is their knee jerk reaction to anything that will defend the US. We have a major league 5th column in this country that seeks its destruction.