They’re complementary technologies, because passkeys can do this in a way that seamlessly coexists with, and is in fact supported by, email magic links for people who don’t yet have a passkey, don’t want a passkey, don’t have the device stability to use passkeys, or would prefer to sign in with a magic link this one time. Despite these drawbacks, I think that proving possession of an email address as a mechanism for signing into an online account is valuable and has its place for many, but not all, websites and apps, because email is decentralized and universal, email account providers are very highly incentivized entities to protect user accounts (e.g.