Why does Jesus constantly silence demons and well meaning people in Mark?

Jesus had power over the demons. They always obeyed his call to silence, however the humans didn't - so great was their joy or amazement at Jesus' power. What is sometimes referred to as the Messianic Secret also appears in the other Gospels, but Mark stresses it because of His emphasis on Jesus as Messiah. He organizes his theme around it which creates a unity in his Gospel. The time had not yet come for Christ's Messiahship to be fully revealed and would not be until after the Resurrection. It also may be because He wished to be able to continue undertaking His work, and was constantly surrounded by people and action as it was.