If they actually were 90% effective we would not see what we do see. Even if that 90% number is true it's the overall system effectiveness, not the effectiveness of the missiles. Since the launcher got hit that was down the throat, the easiest possible intercept and one in which you get multiple engagement cycles. 90% overall, if you get two cycles that means the missiles are 70% effective. Three cycles, that translates to 55% effective. You know enough math to figure this out.You are talking complete nonsense. Russian air defence is about 90% effective against ATACMS.Your best missiles failed to take out rockets that are more than 20 years old. You got some which is what I would expect. And your lesser SAMs were apparently completely unable to hit them. ATACMS has nothing but speed and altitude to get through--basically, the Russian approach. Storm Shadow aka SCALP is more along the US approach--low and subsonic, but hard to see (especially if it can weave through terrain) and hard to hit.
You are only able to reliably hit places which are not covered by Air Defence like beaches, murdering 2 year old babies.
You are talking utter nonsense.
And not even Russia agrees with you on what happened on that beach. That missile wasn't aimed at the beach, but rather you got a partial kill. It could no longer steer but the boom part still went boom. This is a standard problem with shooting down ballistic inbounds--unless you obliterate it with a direct hit you can not realistically tell if it's dead or not. And killing the controls doesn't mean the warhead is dead. We got our lesson in it in Desert Storm (Patriots failing to take out Scud warheads on "successful" intercepts) which is why we have gone to kinetic kill for extreme altitude intercepts.
And note that your S-500 battery should have been able to cover the whole area. Said beach was within the defense zone.