While Israel went astray, the Servant took their iniquity upon Himself and shouldered the blame for Israel. The Servant and Israel are two separate entities. Israel cannot atone for the Gentiles because she is held back by her own sins. So the 'he' here cannot refer the nation of Israel, therefore the Servant cannot be Israel. He made no noise when mistreated and killed, even though he was suffering on behalf of the very ones were persecuting Him.
Mankind is outraged by mistreatment and is always vocal to complain about injustice.
An unusually specific prophecy concerning Yeshua who was crucified among criminals and then placed inside the new tomb of the rich man, Joseph, when He died. Again, a reiteration of the Servant's own innocence in His own suffering. Further proofs this Servant could not be Israel. The Servant died, but Israel is still alive today in spite of millennia of persecution. Israel's continued existence today is one of the greatest proof's of the truth and accuracy of G-d Word.