Sometimes I have to enter a long text in the chat and then submit it. Unfortunately, nobody is used to submit the message just pressing **Enter** button. Then the message is not complete and submitting multiple messages creates a lot of noise.
One good example is the chatting system from Linkedin. At some point they had the same issue. Now it's asking you before sending the first message if you would like the **Enter** to submit the message or you actually want a new line instead.