Because there's two types of storing passwords in plain text. There's the "your password is stored in plaintext in the database" way which everyone agrees is 10 different kinds of stupid, and then there's the "we accidentally logged the body of all requests that went through this system, and it turns out login requests came through here" kind. One is a bad security decision (because you must decide how to store passwords in the DB), and the other is a very easy mistake to make which can go unnoticed for a long time (because you can be attempting to log things completely unrelated to logins).
Same same but different.