That's because you're locked into the x86 paradigm. Look at the leaps and bounds Apple is making with performance/Watt by moving away from x86. This is the cost of legacy.
Architecture emulation like QEMU provides is commonly used, just a matter of how much investment is made into backwards compatibility by those who build your operating system/platform.
Apple works hard to break backwards compatibility every few years, while other operating systems will happily run software from decades ago as they care and invest in not breaking userspace.
Apple really likes being on the bleeding edge of computers, and it often comes at the cost of older programs and features being killed off in that process.
Apple works hard to break backwards compatibility every few years, while other operating systems will happily run software from decades ago as they care and invest in not breaking userspace.