marker that a message has been seen

Hello, I started using discord about a month ago and I have to say that I am very content with what this platform offers. However, there is one little thing that could be done better in my opinion: I would like to know, whether my message has been seen by my friends. Features of that sort are common in other chat apps, so I don't know why discord lacks it. Is it missing on purpose or is it planned to be involved in next updates?