Provide rationale for FLoC being opt-out rather than opt-in

[MarkTiedemann]

I don't understand why the burden to opt-out is placed on users (e.g. disable history data sync) and sites (add Permissions-Policy header).

Is there any documentation about why FLoC is opt-out rather than opt-in?

[michaelkleber]

Regarding sites, see the discussion in #45 (comment).

Regarding history data sync, (1) this is indeed opt-in not opt-out, and (2) synced data is not used to calculate your flock, only as a way for Chrome to ensure certain global privacy protections; see this part of the explainer.

[infostreams]

The reason is that you cannot make money if people have to opt-in to tracking behavior. I mean, come on.

[MarkTiedemann]

Thanks for the pointer, @michaelkleber.

During the Origin Trial, the default for whether a page will be used for FLoC computation will be based on Chrome's existing infrastructure which detects pages that load ads-related resources.

Both the opt-out (via an interest-cohort permissions policy) and the opt-in (via calling the API on a page that did not opt out) will work; the ad resource detection will be the default for pages that don't do either one.

Is ad resource detection (supposed to be) included in the spec or is this just a determining factor during the Origin Trial?

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Regarding history data sync, (1) this is indeed opt-in not opt-out, (...)

Yes, history data sync is indeed opt-in, and yes, among other things, the user must be logged into a Google account and must have ad personalization enabled.

But no user has specifically opted-in to cohort computation. Is that correct?

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Are there any plans to add a setting to enable/disable FLoC to chrome://settings/privacy, chrome://flags or similar?

[michaelkleber]

Is ad resource detection (supposed to be) included in the spec or is this just a determining factor during the Origin Trial?

As in #45 (comment), our expectation for the full launch is to default to pages not contributing, with the opt-out and opt-in both available. But please remember that the point of an Origin Trial is to learn our lessons before the details are fixed — so the final design is still subject to change based on OT feedback.

But no user has specifically opted-in to cohort computation. Is that correct?

Correct.

Are there any plans to add a setting to enable/disable FLoC to chrome://settings/privacy, chrome://flags or similar?

Yes! It's in Chrome 90, which is currently the stable branch. Probably not turned on for everyone quite yet, but soon.

[MarkTiedemann]

Thanks for clarifying, @michaelkleber.