I was just looking at availability using the Resort availability tool and I saw this note on the page:

Due to limited parking availability, we highly recommend all Disney Resort hotel Guests take advantage of our complimentary transportation options. For Guests arriving in their own vehicles, please be advised that only valet parking may be available. For Guests traveling to Epcot, please utilize the Epcot Guest Parking Lot.
This is a recent addition, as I didn't see this when I looked at the site a couple weeks ago.