1. Sometimes we get the impression that John the Baptist invented baptism, but actually, baptism as an outward sign of repentance and cleansing was already practiced by the Jews. They've even found baptismal pools that date back before Jesus' time in Israel.
2. Jesus told the man with the dreaded skin disease not to tell anyone about it. (v44) In contrast, He told the Gesarene demoniac to tell everyone, and he did, so that all Decapolis heard about Jesus as a result.
The man with the dreaded skin disease disobeyed Jesus, to the point that Jesus was mobbed so much that He had to stay away from town.
I wonder if that's why He told him not to tell, whereas Decapolis wasn't His territory so it didn't matter that the former demoniac told?