Like many things, I consider "progressive enhancement" the core of questions like this. Whilst I'm not a fan of "magic link", first and foremost you should offer the old school id and password approach JUST so people don't have to be on some OTHER service they may not want or have access to.
Social media services -- like facebook -- often have the accessibility failing that no JavaScript == no website, no login, and that (depending on the type of site) can land you in hot water legally.
BUT -- there is no reason not to offer it ON TOP of a normal login. It's easy enough to make an old-school conventional login form and registration, and then ENHANCE it with the option for social media logins on top of it.
ALWAYS have a fallback plan!