If you are implementing an emulator, you must insert some jitter to the emulated floppy drive.
Because if there is no jitter, the ROM's calibration code does a division by zero and crashes.
Modern Mac OS also has all sorts of "bugs" that Hackintosh users need to patch or otherwise work around. Since we're doing something that was never intended, I don't really see these as flaws in the OS.
EDIT: I should add, this applies to applications, not just OSs. If you're an Android dev - will your app run on Android 15? Will it work on ChromeOS? Will it run on Fuchsia? If you're writing Windows software - will it run on ARM? If you're making webapps - does they work on Firefox? And maybe it's not worth the effort, especially if you don't plan to be selling the same software in 5 years, or maybe you think you can just deal with those things when you get there, but if you plan to still be in business in a decade then you should plan accordingly.
That said, the limit is more problematic than it initially appears, because USB 3 ports count twice—once for USB 2 devices, and once for USB 3 devices. Some motherboards also use USB under the hood for things like Bluetooth (as do real Macs, btw), and even USB headers which aren't connected to anything will take up space if you don't explicitly exclude them.
2 built-in USB C ports on the top, the I/O card has 2x USB-C and 2x USB 3, and each GPU has 4x USB-C.
So with dual GPUs that's 14 USB ports. Maybe some are implemented via internal hubs?
If not for that, it would in fact go way over, because USB3 ports count twice.
For my sanity would you mind calling it Mac OS X/OS X/macOS? I’m not too picky about you matching them all up to the right release but the moment I see Mac OS my mind jumps to the old one without memory protection ;)