Sadly we've lost that, as more and more apps everywhere are now developed in Electron or other "cross OS" systems. Even Java apps would try a bit harder to match the OS than these "let's create a new UI paradigm for everything" apps that won't even let you open a second window.
Yes, Apple doesn’t care about backwards compatability, so you might have to update your application so that it runs on the latest macOS version, but there’s no way around it.
You either have a gazillion competing frontend APIs to maintain compatability with shit that was written for Windows 3.1, or you don’t care about any of that and end up with almost entirely consistent visual styles across the entire OS.