> The most frustrating change for me was FB (or Messenger later) used to send me an email when I received a message, with the message content inside the email. A few years ago they removed the content from the email and forced me to log into FB or Messenger to see the message. It's extremely user hostile.

You also used to be able to reply to the message by replying to the notification email, so you could be a full conversation participant solely through email without ever opening the app.