You've never read a message with the intention of responding at a later time? I do and if I don't flag it somehow (unread) I will easily forget about it.

Ah, for email, I use flags to mark them that I need to respond. I treat "Read" literally – that means I've seen it. Thanks for the explanation.

My Samsung phone allows the message to be sent to reminder. Iphones don't have something like that?

Then what's the point of having read receipts? Just have them wait until you send them a message

It’s not for the receiver to keep them from knowing you read it, it’s to build a queue of messages you want to reply to (anything unread will be easily marked in the UI for later revisiting next time you get a text or open the app). In this case, marking it unread wouldn’t need to affect the read receipt in any way. Really the unread feature is an ad hoc reply reminder flag.

Ooooh I see. Thanks for the clarification

For the same reason this exists in email.

I like the Archive pattern better. Unread keeps it semantic value as showing you something new arrived, but you're not done with it before you have archived the mail/conversation and it's out of your view.

I think they called it Inbox Zero back in the days when it was all the hype.

But it's not the same paradigm - different message mediums have different communication expectations. And one of the differences between email and texting is that the group of texting people is smaller and more frequent. Therefore it's more efficient to not use the archive pattern for texts. You want the list of people you've messaged to just be there (and not abstracted by a commonly contacted list) easily accessible for continuing the conversation with the history too.

It depends on communication habits too, I suppose.

I only open Messages whenever somebody wrote me (which would automatically un-archive the thread).

Telegram supports archiving, and I use it all the time there.