[orls]

People who fit into <some racial/ethnic/age/gender bucket> spend more time looking at <x products>, fed to advertisers who can tie it to swathes of your other online activity

Even if it’s _theoretically_ coarse data/bucketing, that adds up to a lot of data to help deanonymization and targeting. Even if that’s done in the spirit of “just for ads”, it’s not a big leap to political targeting etc, and with the right data leaks, potentially even actual harassment.