It can be easily proven from historical rabbinical quotes that they believed that Isaiah 53 was speaking of the Messiah. So I guess when you say ‘All Rabbis’ you are only talking about those alive today… Arnold Fruchtembaum, who is a Jewish believer in Jesus, after being raised in a traditional Jewish upbringing, says this:

“To interpret Isaiah 53 as speaking of Messiah is not non-Jewish. In fact, if we are to speak of the traditional Jewish interpretation, it would be that that passage speaks of the Messiah. Today, Rashi’s view has become dominant in Jewish and rabbinic theology. But it is not the Jewish view. Nor is it the traditional Jewish view. Those closer to the time of the original writings, and who had less contact with the Christian apologists, interpreted it as speaking of the Messiah.”

Fruchtenbaum writes this after quoting numerous rabbinical sources. Consider the following quote from Fruchtenbaum's book 'Messianic Christology'

"Among the earliest Targums are those of Jonathan ben Uzziel dating from the first century AD. His Targums on this passage of Isaiah begin with these words: "Behold my servant Messiah shall prosper..." The Targums of Jonathan ben Uzziel were heavily quoted by the early rabbis and he was certainly considered an authority on the Jewish view of Scripture. He definitely considered the Isaiah passage to speak of Messiah. Jonathan ben Uzziel could hardly be accused of adopting the "Christian interpretation." That Jonathan ben Uzziel was not alone in this interpretation becomes clear from a quotation from Rabbi Don Yitzchak Abarbanel from about 1500. While he himself did not accept the view that the Isaiah passage referred to the Messiah, he makes a dramatic admission:

The first question is to ascertain to whom (this scripture) refers: for the learned among the Nazarenes expound it of the man who was crucified in Jerusalem at the end of the second temple and who according to them was the Son of God and took flesh in the virgin's womb as it is stated in their writings. Jonathan ben Uzziel interpreted it in the Targum of the future Messiah; but this is also the opinion of our learned men in the majority of the midrashim.

In spite of Abarbanel's personal view regarding this passage, he freely admits that the majority of the rabbis of the Midrashim took the passage to speak of the Messiah. He thus points out that Jonathan ben Uzziel was not alone in his opinion, but rather this was the Jewish view of the period of the Targumim and the Midrashim."
 

Rabbi Saadyah Ibn Danan (1500 AD) also wrote concerning those who interpret it as Israel –

“One of these, Rabbi Joseph ben Kaspi, was led so far as to say that those who expounded it of the Messiah, who is to be revealed, gave occasion to the heretics to interpret it of Jesus. May God however, forgive him for not having spoken the truth! Our Rabbis, the doctors of the Talmud, deliver their opinions by the power of prophecy, possession a tradition concerning the principles of interpretation… alludes covertly to the King Messiah.”

So Rabbi Saadyah Ibn Danan saw that others who said the Isa 53 spoke of Israel and not the Messiah did not speak the truth and did it because they didn’t want the heretics (Christians) to say that it was about Jesus. Which is exactly what Rashi himself said as I have already mentioned in an earlier email when he said ‘"Since Christians interpret Isaiah 53 as being a prophecy concerning Jesus, we maintain that this is a prophecy concerning the people of Israel."

At least Rashi was being honest as to why he interpreted it this way.

I guess Rabbi Saadyah Ibn Danan’s integrity wouldn’t allow him to interpret Isaiah 53 as being about the nation of Israel however and, as he wrote above, he told the Jewish interpreters of his day to return to the Talmudic interpretation, that this passage refers to the Messiah. Again, the historical view of this passage was of Messiah.

All the best.