I would appreciate it if AO3 could explain how big an issue this actually is. From a subjective POV, I don't personally know anyone who has mentioned this being an issue for them but that doesn't mean it isn't a huge issue and I get that.

However, if it isn't a huge issue then I'd like to see protections for exchange culture, hence 'opt in.'

... at the very least, I agree with the people who'd like to be able to see an indication on the person's gift page that they've turned off gifts outside of their exchange gift so I could add one more step to the treating process to check if they're even open to it before starting down that road.