Then we all have to enter our email twice. Why not just ask for the info you actually want: login with password or login with sso buttons
Log in with Corp acme. Log in with palantir. Log in with Facebook (Corp). Log in with Facebook (end user)... Etc.
You'd have to iterate through every customer with SAML / OIDC set up.
Even if you are just using end user, it's sometimes confusing if there are 10+ options because you have to remember... Ok not only do I gotta remember my email I used, how did I originally sign up? .. was it with Google? With Facebook... No wait did I use email and password...