According to the announcement, these shortcuts will help make it easier for users to use certain features. For example, there is now a “@everyone” tag which will alert everyone in a group chat at once. Prior to this, users could only “@” specific people, so this change will make it easier to ping everyone at once, similar to the “@everyone” feature on apps like Discord.
There will also be new shortcuts like “/silent” that lets you send a message without a notification, perfect if you know the other person might be busy and you don’t want to disturb them but also want to send a message at the same time. Then there will also be shortcuts for sending money over Messenger, and in the future, there will be other shortcuts like “/gif” that will make it easier for users to find GIFs in their chat.
Some of these shortcuts appear to be exclusive to iOS for now, but presumably it should eventually make its way onto Android.