Although it may perturb some Jews to hear Christians argue that Messiah will destroy a large number of people just prior to, or as part-and-parcel of the redemption that's the foyer to the messianic-age, nevertheless, the prism used to interpret the messianic-prophesies determines whether or not that is or isn't the case. Many Jewish sages who might agree Messiah is a metaphor for certain kinds of actions and events, as well being a type of the nation of Israel as a whole, nevertheless tend to concede that the Tanakh also teaches of a singular Messiah who's the archetype for all the messianic actions and events that might preceed his eventual unveiling before all the world. Maimonides, for instance, teaches that anyone who rejects the arrival of a singular Messiah is not teaching Judaism proper (or at least not properly).
As long as we teach Judaism properly, at least so far as Maimonides is concerned, we can say: Yes Virginia, Messiah will indeed destroy a large swath of people. And when we find out precisely who's included in the lot of the dead and dying we might begin to understand why so many Jewish exegetes aren't as straightforward in their interpretation of the numerous prophetic passages that say so as they should be. Carefully exegeted, Isaiah chapter 63 paints a picture very few Jews would like to look at. I mean who could deny that it's tastelessness of the highest order to paint a picture of the greatest hero of the Bible from his corpse? Faithfully exegeted, that's precisely what Isaiah chapter 63 does.
John