Stayed at the Westin Harbour Castle, Toronto last weekend. Booked via Expedia. Called hotel ahead to inquire about Titanium benefits with Expedia booking and to add my Bonvoy number to the reservation.
Was informed of and received all benefits except Bonvoy night credit, room cost points, welcome points, and 6X Amex Brilliant points. Received warm member welcome, upgraded room, free full (and magnificent buffet breakfast for two each morning), late checkout, etc.
I feel the policy is quite fair.