I think it's true that Apple doesn't show your contacts status of other people in the Messages app itself but it does show your contacts alternative way to mess

I think it's true that Apple doesn't show your contacts status of other people in the Messages app itself but it does show your contacts alternative way to message if you have it added - looking at a random contact I see a button inside Contacts to launch a chat via FB Messenger there. While not exactly the same it is useful