Why people say good morning (or something like that) on chat after a night?
I mean, I see chats as one continuous conversation and unless the conversation has been properly ended, it shouldn't be necessary even if a night has passed.
If there’s been a pause of several hours, people consider it a new conversation. “Good morning” implies that the speaker assumes other participants have slept overnight.
Oh I see, even if chats are organised by person, the conversation has ended (even if improperly) if X time has passed. So people organise mentally the conversations as individual interactions, it is the social component that overrides the digital organisation.
Reading a bit into "ended improperly", one possibility of them saying good morning could be if after they stopped talking late at night you still added 10 or so more messages in a row. Hehe. I used to get that alot. Basically both sincere and sarcastic at the same time. To let you know they are awake now and caught up on your continued posts after they fell asleep, as well as poke a bit of fun that you maybe missed a "too subtle for us" hint that the other person was going to sleep before you kept posting.