>or offers some competitive UX advantage (although this reason is shrinking all the time).

As a user, properly implemented desktop interface will always beat web. By properly, I mean obeying shortcut keys and conventions of the desktop world. Having alt+letter assignments to boxes and functions, Tab moves between elements, pressing PageUp/PageDown while in a text entry area for a chat window scrolls the chat history above and not the text entry area (looking at you SimpleX), etc.

Sorry, not sorry. Web interface is interface-smell, and I avoid it as much as possible. Give me a TUI before a webpage.