Only the GUI part is relevant for this discussion as this is what Qt is know for. Other modules also have different Rust crates equivalent, or are really niche and nobody uses them.

that's really not true. There are thousands of projects using e.g.

QtSerialPort (https://github.com/search?q=include+QSerialPort&type=code)

Qt3D (https://github.com/search?q=include+Qt3D&type=code)

QtWebSockets (https://github.com/search?q=include+Qt3D&type=code)

QtSensors (https://github.com/search?q=include+qtsensors&type=code)

Qt SCXML (https://github.com/search?q=include+qstatemachine&type=code)

etc etc..

Qt's value is as an app framework where you can assume interoperation across the same async runtime and enjoy a cohesive set of APIs for all your app's needs.