Comment by abhayaya

Imho, legally, one should always be 'opted out' of 'forced mingling of your ideas' without deliberately opting in. Same as for advertising, click-through tracking, and sociopsycho/marketing metrics. Like the old firewall rule (easier to handle opt-in/out that way than firewalls; like, how many people can run a firewall that way now?). Users should have it right in front of their face when they install something or register, too, not hidden among options. It might take the user five or ten more minutes to get to use the app but worth it.