For every person who has a reason to want to be in the room before 4:00 p.m. there is another person with what they think is an equally compelling reason to stay past the 11:00 a.m. check-out. There is no way that both groups can be satisifed. Sometimes people get lucky and get these requests met. However, since
DVC resorts tend to be pretty much at capacity all the time, DVC has made it a point to stress in the VM and elsewhere that check-in is 4:00 p.m. and check-out 11:00 a.m. and early check-ins and late check-outs are not granted.
As I mentioned, some hotels will not even begin the check-ins until the stated time. This can make for ridiculous lines. DVC at least lets you get in, drop your bags and head out to the parks. They just can't guarantee you your actual room.
Here's the policy from the member site:
Reminder: Check-in and Check-out Policies
Please remember that you may "check-in" anytime on your arrival day (take care of all front desk paperwork, receive your Walt Disney World® Resort ID card, Theme Park tickets, etc.), but you may not necessarily be able to begin occupying your room until after 4:00 p.m. (official check-in time). Please notify the front desk or Member Services if you're planning a late arrival or if you need special arrangements.
If you arrive at your resort before 4:00 p.m., your luggage may be stored by bell services staff until your room is ready. Likewise, check-out is by 11:00 a.m. If you'd like to stay and enjoy the resort on your day of departure, simply check-out of your room by 11:00 a.m. and leave your luggage with the bell services staff until it's time for you to leave. For the consideration of all Guests, as well as our busy housekeeping staff, we ask that you please do your best to respect these time frames. In order to ensure that all rooms will be ready for all incoming Members and Guests, no late check-outs are available.