Earlier quoted context omitted.
Yes, running experiments on unknowning and unconsenting users is unethical, especially when the metrics being optimized for usually aren't in the users' best interests. The widespread acceptance for this behaviour could definitely be classified as brain damage.
> the metrics being optimized for usually aren't in the users' best interests Do you have any source for that? If you truly believe that Firefox is optimizing metrics that aren't in the users' best interest in general, why are you even using said software in the first place?
I don't see this as having users best interests in mind.