As weird as this sounds, that's not actually true. I can tell you with some level of authority that Marriott is well aware that many Titaniums or other Bonvoy level members do not stay at Marriott properties through LV and they're not worried with that fact. Why? They understand that most Vegas visitors need to be close to where they need to be for the purpose of the trip. For many people, that's the strip, and most people will not sacrifice location in place of earning points. Off-strip Marriott's can't compete with casino hotels on the strip. They're often cheaper and far more convenient. It's why the MGM deal was crucial for them. It's why Hilton offered Resorts World a fairly advantageous franchising deal. They know Vegas strip bookings doesn't cannibalize bookings from their other properties. The general sales and marketing strategy for the "off-site" Marriott hotels in LV are to attract those having meeting/conventions within their own four walls or very close-by (The LV Marriott, Westin, and the Renaissance).