I'd say, ALL sites should stop asking for username and password from other sites (which they don't control[1]).
It's bad when you get screwed, for obvious reasons.
It's also bad when you don't get screwed because it reinforces your false sense of security in an inherently insecure practice.
[1] I don't mind as much about situations like logging in to Youtube with your Google credentials since I know google controls both sites.
