True, but if you get a new phone and your blocked numbers list is reset, or they send messages from a different number, then you could get them again in the future. I see this often because there are multiple people in that campaign that will all reach out to people with their own phone numbers. Opting out prevents that for legitimate donor campaigns (you are removed from the list for all of the solicitors associated with that campaign), but obviously not for scams. There is no harm in doing both, and I would recommend that (it’s what I do).