No, you're absolutely right. Hiding a message behind a login is essential linkedin style click baiting essentially.

I agree with you, but it's easier for those companies to just do one option, rather than offer user/customer choices which would create additional effort both technical on the backend and legally.

It's annoying, but from a data security point of view it makes sense, personal information like that is more secure behind the login on their website than in an e-mail in plain text.