The fastest way to lose a channel is to over-use it. A guest who receives a marketing message on WhatsApp blocks the number, and the booking confirmation they actually wanted goes with it.
Because the opt-in is per event rather than per property, a booking confirmation and a check-in reminder can go to WhatsApp while a newsletter stays on email.
Staff alerts route separately from guest messages even when they follow the same event, so an operations group can be noisy without the guest experiencing any of it.
A property that decides a message does not belong anywhere simply turns the event off, and nothing sends.