His ult lasts what? 3 seconds? EDIT: 4 seconds
If Rath knocks you up and silences you then poof there goes any of the counters you just said for 2 seconds. In which you are then running and not looking towards him so even if you survived until that last second you would have to take the time to turn around and CC him.
The only characters that can even survive this are characters with inate mobility (thorn) and tanky as hell characters (montana). Depending on who you play, (orendi and oscar mike for example) have no menas of countering Rath. If he kills you late game you simply line yourself up to be killed by the same combo again.
