As a resort guest you may park for free at other resorts while visiting those resorts. Everywhere in the world, when you are done with your activities at one place and going elsewhere you are expected to take your car with you.
Exception: When you use the valet for parking at a Disney's resort, one fee covers an unlimited stay plus unlimited valet lot hopping (not including tips).
Exception: Walt Disney World allows you to park at one theme park or at a resort you are staying at and use Disney transportation to go to any point in WDW using Disney transportation.
Philosophical question for you: Suppose you arrive at the resort in your car for your restaurant reservation (ADR) and a portion of the lot has been reserved for guests staying at that resort and the remaining parking spaces are all taken? What would you do? What would you suggest?
One thing I would like to see is a system of kiosks at resorts where you can renew a 3 hour parking limit. You would not have to wait until 2 hours and 55 minutes into your 3 hour stay to renew but your next free parking increment runs 3 hours from when you renew. From time to time there may be additional mandatory renewal time windows such as during the fireworks at a nearby park.