That seems interesting. Have there been any studies on user dropoff due to this scheme? Any well known sites using it? Would you recommend doing this exclusively?
Slack did (do? I no longer use it) it, Scaleway (https://www.scaleway.com/en/docs/console-magic-link-authenti...), medium.com, https://www.topicbox.com/ at least.
Yes (unless you are launching an email provider or an end to end encrypted service), because it reduces the number of passwords users have to keep (one of the biggest problem of our time, password managers are not a viable / good solution) and it reduces your attack surface (you no longer have to store password hashes nor can't chose an insecure hash function).