I should be able to fire up a BASIC script from 1970 and have it still run. It shouldn't require me hours of hunting retro-computing websites for the right simulators - it should just be part of the OS.
I don't care how - whether that be emulation, or maintaining direct compatibility.
A set of emulators for all ancient computing platforms only comes in at a few megabytes, so there really isn't an excuse not to include it.
Why you say? Two reasons: 1. maintaining backwards compatibility isn't hard - you just switch to emulation every time you want to 'get rid of cruft', and then what happens inside the emulated container can be frozen in time and requires no maintanance. 2. Every time one breaks a legacy bit of code, all the users of that code have to do some work to re-invent it. It would be like shredding Leonardo da vinci's work just because we have better painters now.
Mac actually took great pains to be backwards compatible until relatively recently. PPC's could run 68k programs, OSX could run tradition MacOS programs, and x86 macs could even run PPC programs.
And Linux Desktop can't run programs not in its repo unless you want to compile it from source.
So what does that tell us? Well, there at least appears to be a pretty strong correlation between compatibility and success with desktop OSs.
I legit see more Microsoft stuff all around, Linux stuff close second.