> Why on earth would anyone want to learn Win32 in 2019?
Because it's the native API on the most common desktop OS?
Because it's the native API on the most common desktop OS?
For example if you work on a game engine or toolset then you must know Win32 - especially if you work on the tools, even if you are using a wrapper like wxWidgets or Qt.
The only time where you can avoid Win32 is if you're using something that completely abstracts away the entire system, like Java Swing or a web browser.