I'd say there are times when bad data is worse than no data.
Consider that the farther away you get from it, the parties involved are either unaware or unwilling to treat it as bad data, so they make make harmful decisions.
So if someone says that opt-in data is useless, I'd say that out-out data is just as useless.
And then we have to pretend that implementation, collection and analysis and then further actions would make it worthwhile.