Chatgpt.com is essentially a CRUD app. What you're saying here amounts to saying that it could conceivably have been designed to work dramatically differently from all other CRUD apps. And obviously that's true, but why would it be?
It's a website! You submit text, that you'll view or edit later, so the server stores it. How is that controversial to a HN audience?
Also:
> the clients don't need to be running at the same time if you have a third device that's always on
An always-on device that stores data in order to sync it to clients is a server.
TBH it sounds like you're just imagining a very different service than the one openAI operates. You're imagining something where you send an input, the server returns an output - and after that they're out of the equation, and storing the output somewhere is a separate concern that could be left up to the user.
But the service they actually operate is functionally a collaborative document editor - the chat histories are basically rich text docs that you can view, edit, archive, share with others, and which are integrated with various server-side tools. And the document very obviously needs to be stored on the server to do all those things.
It's a website! You submit text, that you'll view or edit later, so the server stores it. How is that controversial to a HN audience?
Also:
> the clients don't need to be running at the same time if you have a third device that's always on
An always-on device that stores data in order to sync it to clients is a server.