I wasn't making an argument either way about retracting messages. I was just surprised that someone would think that the DMs are obviously like e-mail when the

I wasn't making an argument either way about retracting messages. I was just surprised that someone would think that the DMs are obviously like e-mail when the UI looks like FB Messenger or Hangouts and message storage and transmission is controlled by a single company. I'm still curious to know how it's like e-mail.