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.