This is nothing about 'protection' for the guest... it is entirely about Marriott wanting to control things and make it more difficult and annoying to book an award stay for somebody else, or have a family member check in early under a reservation you booked.

They changed the 'policy' for vacationclub owners who are renting out their week to somebody else also and make it obnoxious with wanting to have forms filled out well in advance of who is staying... and in fact unrealistically in advance like at least a month ahead of the stay. That is also entirely about Marriott trying to restrict rentals of owner weeks since they aren't getting money from it.