If it’s really about what the software does, then the conversation would be about exposing proper APIs that let me view the data, query it, schedule operations

If it’s really about what the software does, then the conversation would be about exposing proper APIs that let me view the data, query it, schedule operations on it, etc. But then offering a shinier/slightly more bespoke way of doing that becomes a competitive advantage for your product, and now you get why everyone wants to build their own custom UI. The reason why the aforelinked to Open UI project will never be the One and Only way to build UIs on the web is because there’d too much economic value in being able to do precisely what it can’t do!