The thing is that Messiah is a spirit (Deuteronomy 23:14), and it is because fallen humans have a notorious struggle to come back into that reality (Isaiah 59:1-2, Matthew 18:10), as evidenced in that Matthew 21 parable where they kept rejecting His prophets, it became necessary for Him to come in first-person so that we could recognise Him (John 15:22, John 1:11-12).
We who know the spirit of Messiah are able to recognise Him wherever He appears, whomever He appears through, and even to recognise whenever He speaks through us! .. so it was for the faithful ones in the OT, we can reasonably expect that John the Baptist knew Him that way too.
What you are describing is not so unusual, but rather fairly typical of the world's way of regarding celebrities. It's inferior for people of the Jewish faith to regard celebrities that way though, because we do not show favouritism - men are only men, and a man is either right or wrong at any time. When you look at the stories of Daniel, Shadrach, Meshach and Abednego with King Nebuchadnezzar, Mordechai with Haman, even with Jesus and the Roman Centurion whom He commended for having greater faith than any He had found in Israel.. it's just not like us to grovel that way. Even Jesus kept telling people to keep His miracles secret, and He kept escaping the crowds to be alone, because it's just not a very nice way to be treated. Celebrities can tell you that too.
So John the Baptist already had his relationship with Messiah in the spirit, and there wasn't really anything that he needed to follow Jesus in order to gain, but he still had an opportunity to keep preaching The Way to those who hadn't yet found it, and as Adonai's servant, that was his priority.
.. plus, when you mentioned seemingly unimportant details, there's a big void of information in the bible about how the time became ripe for Messiah's appearance in the flesh - though it was big enough news for Herod to kill the babies, we aren't told much of the political and religious climate of the time. I only said this because where you have suggested "nevertheless was a Christian before it was cool", it seems to suggest that you think being Christian is something that became cool after the resurrection .. whereas what Christianity is from the POV of John the Baptist and Jesus Christ, is the bringing of the real kingdom of God against the crony establishments that were exploiting God's name, and I'd suggest that reading the scriptures in context of the fact that the crony religious leaders of the time had become so unable to withstand the Romans and were even paying tax to them, had created an environment conducive to the rise of "renegade preachers" that could easily out-speak the religious leaders (as it is in the present age of Christianity, the "a marvel and a wonder - so the wisdom of their wise will perish" Isaiah 29:14).
