So, to access your bank now crackers just need to get in to your email (which may be true anyway, of course 2FA helps in both cases).
The benefits of sign-in links are: a) you don't have to remember gazilion of passwords b) you don't have to use password managers c) you can setup a really strong passphrase for your email and actually remember it because it's the only one you have to. And of course set up strong MFA or whatever d) you don't have to setup MFAs on services and giving them more personal info(phone number) than they really need e) for me as a developer it's also easier to implement actually