But people get their room before 4pm often. In most my trips I got it often after lunch. Why not say after 1pm if it means there is no guarantee anyway? Why after 4pm, a time that is reasonable after the normal hotel checkin? Why not after 2pm. Why not after 10am? The exact policy should then be anytime during the day.
And I may be wrong but it used to be "at 4pm", they later changed it "after 4pm" because creating confusion on the policy is easier than strive to improve the service.
BTW I have inquired MS about this and they said they cannot guarantee a room ready for 4pm, but they try to have rooms ready by that time.
Of course they get in earlier. And why - because they want to set the expectation that it won't be until at least 4pm. I suspect that 90% of the time rooms are ready by 4pm. But sometimes some of the staff calls in sick. Or they discover someone has smoked a lot of danky weed in the room and it needs a chemical freshener and some time to let the smell dissipate. Or someone's kid got sick all over the mattress and it needs to be steamed. Or bedbugs have arrived. And that can delay things by hours.
One thing Disney used to be very good at was managing expectations. They would tell you a line was 45 minutes, and it would be 35 and you'd be delighted. They'd tell you check in was after 4, and you'd be delighted with your 3pm availability. That's what after 4 is about. But it is after 4. Its always been after 4. DVC members should be aware they bought into a system that operates at very high capacity and sometimes after 4 means 6 - or even later - if there are hiccups in turning over rooms. And make backup plans. This is part of the reason that you can get a room for what ends up costing a member less than $100 a night - because we aren't paying for excess capacity in housekeeping or in rooms.
The real disappointment is when you wait and then the room still smells like someone held a kegger and it didn't get properly cleaned. THAT'S a problem. Waiting until 6pm for a very small minority of reservations - that's the model.