John lived under the old covenant. The new covenant, prophesied beforehand, was not yet in effect.
Once the new covenant was in effect (at Jesus’ death, Heb. 8-9, etc.), His apostles preached baptism in His name. Some didn’t believe this gospel. Those who did were baptized.
Can any one show me where the Apostles who came form John were rebaptized? the only one I read of is Paul, and he was not one of the 12.