Not like me to agree with the FunkMaster, but I'm going to, in a qualified way.
I don't think the purpose of the "prophecies" is to enable Messiah identification. The OT Messianic tradition is an expression of the national religious and social aspirations and dreams of ancient Israel. Other traditions have similar lists of hopes and aspirations "when the gods return", or "on arrival at paradise". It is perfectly coherent to argue that Jesus will fulfil those aspirations when He brings in the "Kingdom of God", which He was quite clear is only currently present "within" His followers. He told Pilate that His kingdom was "not of this world". It is
internally coherent, if you've already accepted
a priori that Jesus is the Messiah.
But the "proof" of Jesus' Messiahship is not to be found here - it is to be found in the experience that He is alive today. His claims are vindicated by His resurrection. This, of course, moves the whole business onto the realms of faith, and John is quite correct that we can't "prove it".
Don't imagine the early church wasn't aware of this:
1 Corinthians
22Jews demand miraculous signs and Greeks look for wisdom, 23but we preach Christ crucified: a stumbling block to Jews and foolishness to Gentiles,
I'll let this serve as my final post on the "Genealogies" thread as well. I know I've not convinced anyone, but that was not my intention. Merely to explain what I think is going on. I don't think I really have much more to say on the topic.