It reminds me of stories I've heard about the Cold War and how Soviet scientists and engineers had very little exchange or trade with the West, but made wristwatches and cameras and manned rockets, almost in a parallel universe. These things coexisted in time with the Western stuff, but little to nothing in the supply chain was shared; these artifacts were essentially from a separate world.
That's how it felt as a Mac user in the 80s and 90s. In the early days you couldn't swap a mouse between a Mac and an IBM PC, much less a hard drive or printer. And most software was written pretty much from the ground up for a single platform as well.
And I remember often thinking how much that sucked. My sister had that cool game that ran on her DOS machine at college, or heck, she just had a file on a floppy disk but I couldn't read it on my Mac.
Now so much has been standardized - everything is USB or Wifi or Bluetooth or HTML or REST. Chrom(ium|e) or Firefox render pages the same on Mac or Windows or Linux. Connect any keyboard or webcam or whatever via USB. Share files between platforms with no issues. Electron apps run anywhere.
These days it feels like Mac developers (even inside of Apple) are no longer a continent away from other developers. Coding skills are probably more transferable these days, so there's probably more turnover in the Apple development ranks. There's certainly more influence from web design and mobile design rather than a small number of very opinionated people saying "this is how a Macintosh application should work".
And I guess that's ok. As a positive I don't have the cross-platform woes anymore. And perhaps the price to be paid is that the Mac platform is less cohesive and more cosmopolitan (in the sense that it draws influence, sometimes messily, from all over).