If it won't make the model worse when you opt out, then you have to find a way to make sure it makes the model worse, so they'll opt in.

It's like how LG TVs make you consent to recording and uploading everything you say in the vicinity, or else you can't have voice commands, which they explain is because it would be illegal to analyze sound inputs for the voice commands without that consent. It's not true, of course, but it sounds true and it makes you want to consent.