[acaloiar]

Facebook is able to realize outsize cross-web tracking benefits by having you logged in as long as possible. Few other companies are able to realize comparable benefits because they don't have the same ad-serving aspirations coupled with "Login with Facebook" reach.

Google is comparable, but it's too risky for them to have so many magic links hanging around in customer inboxes, because Google identities tend to be tied to far more sensitive 3rd party applications. Which is not to say that there are no sensitive applications with "Login with Facebook", but I'll argue there are fewer.