Opt-in is almost always more ethical, but even the notion of opt-out has been eroded by tech companies and devs. A proper opt-out policy would be to inform the interested parties BEFORE taking any steps to include them (e.g. collecting their data, scraping their code, connecting their account), and giving them a sufficient interval to opt-out BEFORE actinv in that intention. Letting someone "opt out" halfway through the process isn't really an opt-out.