Here' s an semiauot advantage that most people don' t realize-
When sound of the bolt cycling is covered up by the muzzle report. If you were to need a quick follow up shot without spooking game before the shot like say for instance if you somehow had a hornet sting you on the back of the neck causing you to jerk your shot causing you to miss a record book buck, cycling the bolt on a bolt action will make enough noise to draw the animals attention to where you are at, whereas the game will never hear your action cylcling with a semiauto.

The first muzzle report alone will not draw attention to you because down range the animal will hear the loud splat of the bullet hitting, brush, trees, or mud in one direction and hear a loud boom coming from another.