Not to mention that B2B SaaS needs to provide the login methods that their customers need for their operations, and these typically rely on Google, Microsoft, Okta, etc.

I work on auth for a European startup and this is the case.

That users choose to link their account to Google when they can does not surprise me.

What surprises me is that if they cannot do it, they will just leave. The post says it is a "conversion killer".

It's not so much that they'll leave, as much as some percentage will abandon during the signup flow. I know somewhere out there are statistics on those who have to click a link in an email only to get distracted by other emails, to say nothing of the time to fill out forms, create a password, save to password manager, open your 2FA app for the more advanced users, etc.

The higher the friction, the lower the probability of conversion. E.g. Amazon famously found every 100ms of latency costs them 1% in sales.

At its most simplified, this can be thought of as a simple function of time — the more time something requires, the higher chance something else happens during that time, invalidating the original task.

The best sign-in flow is none at all — that's what e.g. Discord does. They let you use the app immediately, with an automatically created provisional account. Amazing user experience.

This applies universally — convenience is everything.

> I also avoid it because I'm concerned about being over-reliant on google (what if they close my account?)

Most if the "sign-in with google" accounts I have seen treat it as a shortcut to creating and logging in with an account with the primary email address of the Google account. So you can hit "reset password" and get a conventional password log-in to an account you previously made with the Google auth. If you get locked out of google, it's NBD.

Of course, this is probably not universally the case.

Does Google even let you create an account without Gmail anymore?

Yes. There is a "Use your existing email address" button in the create account dialog.

Passkey signup could be almost as easy. Type email address, click register, invoke WebAuthn flow (which is no more complex than social registration), done. Maybe you need email address validation for some reason, in which case it’s a wee bit more complex. Ideally there would never even be an option to make a password unless passkeys are unavailable.

> Ideally there would never even be an option to make a password unless passkeys are unavailable.

I like passkeys, but ideally it should always be an option to make a password, too.

Sure, and there’s a UI for rejecting passkey enrollment. I’m just saying that there’s no need for anywhere near as many clicks to enroll a passkey as are often needed.