With my house key, they can get to my email, so email permissions are narrower than house permissions. Someone with access to my house can definitely cause more

With my house key, they can get to my email, so email permissions are narrower than house permissions. Someone with access to my house can definitely cause more trouble than someone who only has access to my email. It's not just friends either btw, I also give house keys to the cleaners, etc. If your email is so super secret, then you probably shouldn't trust Yahoo or Microsoft with it either, btw. I'm not saying that there aren't security issues, but you need some perspective here. Facebook is just as secure as Yahoo, so letting them use your Yahoo password really isn't that big of a deal.