Well, actually he did:
8 Produce fruit in keeping with repentance. And do not begin to say to yourselves, ‘We have Abraham as our father.’ For I tell you that out of these stones God can raise up children for Abraham. 9 The ax is already at the root of the trees, and every tree that does not produce good fruit will be cut down and thrown into the fire.”
10 “What should we do then?” the crowd asked.
11 John answered, “Anyone who has two shirts should share with the one who has none, and anyone who has food should do the same.”
12 Even tax collectors came to be baptized. “Teacher,” they asked, “what should we do?”
13 “Don’t collect any more than you are required to,” he told them.
14 Then some soldiers asked him, “And what should we do?”
He replied, “Don’t extort money and don’t accuse people falsely—be content with your pay.” (Luke 3:8-14 NIV)
So again I say. John called people to repentance via water baptism which all by itself births an earthbound, natural nation and kingdom of God. As well and good as that is, Jesus said that is not enough. You must also be born of the Spirit, or from above.
This is another subject that needs to be in it's own thread. (You're being derailed by the curious habit of believers to instantly think 'self righteousness' at every mention of 'law'. This has NOTHING to do with that.)
The point I'm making, and which you are missing is, repentance to the righteousness of God and away from sin via water baptism only produces what Paul calls a person 'born according to the flesh'. Like Jesus, Paul says a person born only of the waters of repentance back to the righteousness of God is not the one who will see the kingdom. A person must also be born of the Spirit to see the kingdom of God.
Your "theory" seems to conflict with what Jesus taught us -
The law and the prophets were
until John. Since that time
the kingdom of God has been preached, and everyone is pressing into it.
As you can see, the law was until John.
Since that time, the kingdom of God is announced and made available by faith.
The law is not of faith.
Baptism was made available by John the baptist.
John did not follow the law of Moses.
John did not sacrifice animals for his sin, nor did he submit himself to the Levitical priesthood.
John believed [obeyed] God [His Voice] like Abraham, and it was credited to him as righteousness, like Abraham.
Abraham was the father on many nations, yet he did not keep the law of Moses.
For it is written -
And this I say, that the law,
which was four hundred and thirty years later, cannot annul the covenant that was confirmed before by God in Christ...
The law of Moses has vanished away.
The righteous requirement of the law is obedience, which was from the beginning, as Adam disobeyed and brought death, through his sin upon all mankind.
God's Law has been in the earth since the beginning, as there were transgressions before the law of Moses.
What purpose then does the law serve?
It was added because of transgressions, till the Seed should come to whom the promise was made; and it was appointed through angels by the hand of a mediator.
Where there is no law, there is no transgressions.
Paul said the very purpose of the law was
because of the transgressions that took place prior to the law of Moses.
The Seed has come, the law of Moses has vanished away.
Can we learn principles from the law, yes.
Can we teach from the shadows and types from the law, yes.
Is the law good, yes.
Are we under the law, NO!
JLB