I would request that the moderator team change this sensationalist thread title to something more balanced, such as “Marriott changes terms and conditions language for upgrades”

As always, properties that were not being generous with upgrades will continue to be so, and properties that were being generous with upgrades will continue to be so.

The terms always had the fact that the “best room
available” would be determined by the hotel - making that language particularly useless as a leverage point of the guest against the hotel. Plus, we all know that the stay is already starting off wrong if a guest had to throw the T&Cs in to resolve an upgrade dispute with a property - they have made their intentions known.