> No one wanted to use those or make them for other people.

but why not?

personally i find it much easier to track my food, workouts, daily diaries etc. in ChatGPT/Claude as I already use them for everything else. no need for a standalone app when the app could simply plugin into ChatGPT.

wondering if it's a UX problem or a more fundamental one like platform risks

It not really even an app. It's just a thread. You'd be better off with something like Cursor where you are reading and writing files on your own drive.