Facebook abruptly switched everyone's default email address to the @facebook.com account you've never used. [...] If you go to your profile (or anyone else's), you'll see the @facebook.com email account listed -- which just forwards to your Facebook messages inbox -- and none of your others. They've all been hidden in a ham-handed attempt to make the Facebook inbox relevant.
Apparently Google Plus also changed something in the last week or so. I started getting mail telling me that people were "sharing" things with me, but apparently their definition of "sharing" is, "someone you don't know added you to a 'circle' so we're going to mail you several times a day telling you that they made a public post."
Thus continuing my longstanding tradition of only ever logging in to Google Plus when I need to play whack-a-mole and un-check another new checkbox to get them to stop mailing me.
I'm sure every time I do that, they count me as an "active user".