Why is Quick Replies missing in the Facebook Inbox?

Why is Quick Replies missing in the Facebook Inbox?

At the moment, Facebook Inbox does not support the functionality of showing Quick Reply buttons, as it might lead to user confusion of mistakenly thinking the message has not been sent out. Thus, the button does not show in the Page's Facebook Inbox by design as the Page is the one sending the quick replies. The buttons will show up for the Receiver instead.