More time to continue the rotation of the face around to be less open is one reason for offset. The other one is slighly putting the hands a little more in front of the clubface to supposedly allow the golfer to have more of a chance to hit down on the shot. And another one is that the more offset on the head, the farther back is the CG from the centerline of the hosel bore, which is a factor in launch angle for golfers with a later release.
But no matter what, the human golf swing very definitely can be quite different in many aspects from one golfer to the next. Not all golfers rotate the hands/arms the same way on the downswing through impact. Some golfers pronate and turn the right hand over the left at some point before, during or after impact. Some golfers do not pronate through impact and can leave the right hand under the left, so for these swings, offset won't do much of anything with respect to the rotation of the clubface at impact.
Also, some golfers release the club so early that no matter if you had 30mm of offset on the clubhead, this still won't bring about a downward angle of attack at impact.
But the fact still does remain there most definitely are many golfers who do swing in such a way with their release that the presence of more vs less offset can cause a difference in shot direction and shot height for sure.