John's life in the wilderness was not one without purpose. He fulfilled prophecy and was heralding the coming of the Messiah.
If someone were to do that today, I would question why, and what Biblical instruction they find to do so? Are we all John the Baptist, to live like him?
If a Christian today were to go out into the wilderness and live like John, I don't see how they would gather together with the saints, be part of a church body or celebrate the Lord's Supper.
I don't see the purpose of a 'wilderness prophet' today.
The last prophet was John himself, and they were all looking forward to the Messiah.
With Jesus come, and us rejoicing in His reign and enjoying Him, I don't see why we'd need a wilderness prophet.