That ones because users like choice. They need to look up who you are to know how you’ve chosen to authenticate. At least, that’s how it started. Some could be doing it because the big kids are, but that’s why the big kids do.
And they support choice because businesses want to use their login infrastructure and refuse to share. So you enter “user@businessOrUniversity.com.edu” and it forwards you to your institutional login.
That ones because users like choice. They need to look up who you are to know how you’ve chosen to authenticate. At least, that’s how it started. Some could be doing it because the big kids are, but that’s why the big kids do.
And they support choice because businesses want to use their login infrastructure and refuse to share. So you enter “user@businessOrUniversity.com.edu” and it forwards you to your institutional login.