In short, total BS. It's an effort to thwart rental of units. As for those who experience the problem of trying to change the name at the time of booking and having the State field show up invalid in red, it's 100% related. Being able to change the name at booking bypasses the form. The form has a checkbox that you verify "this is not commercial activity, and if we decide it is, we can cancel the reservation at our discretion with zero liability" - which is not included in the online booking. The form is an extra release of liability to crack down on renters. And on the form you are also agreeing to hold them not responsible if they experience a data breach due to their mismanaged IT dept.
But really, 30 days? As if it really matters if 29, 15 or 5. Draconian is the best description used so far. They aren't running FBI background checks on guests.
Dead serious, time for a lawsuit. It is a material change in terms and conditions from when we became owners, without a clearly stated reason for doing so, such is compliance with new laws. Essentially Marriott's efforts to "change the rules" now creates a legal claim called "fraud in the inducement" and is illegal. It devalues every single ownership, whether you are renting or not.