That's true for Windows, but it isn't true for macOS - Apple released its first x86 computer in 2006 and its last operating system capable of running PPC softwa

That's true for Windows, but it isn't true for macOS - Apple released its first x86 computer in 2006 and its last operating system capable of running PPC software in 2009 - no 2005 software could run on a 2009 Mac. Apple released its first operating system able to run x86-64 apps in 2007, and the last OS capable of running x86 apps in 2017 - no 2006 software could run on a 2017 Mac (and lots of post-2006 software can't either, because developers were in no hurry to switch to 64-bit builds). My employer makes commercial cross platform software for Windows and Linux (and in decades past, various commercial Unixes). If you install the 32-bit libraries, you can run our software from 8 years ago just fine on modern Linux. If you also use LD_PRELOAD to replace a couple of C library functions with ones that don't take the `restrict` type qualifier on their arguments too seriously, then you can run our software from 16 years ago just fine too. Commercial software didn't come to Linux in the volume that it came to Windows and macOS because the users didn't come to Linux in the volume they came to Windows and macOS. And the users didn't come because Mac and Windows mostly just work, that was far from the case for Linux in the late 90s and early 2000s when the total number of desktop and laptops in service was exploding. And these days Linux mostly just works - I can't remember the last time I had to futz with an X11 modeline or a kernel module - but its too late.