If only those trillions of dollars of market cap and hundreds of billions of dollars in revenue could support...a couple dozen small teams maintaining legacy support. For the old hardware, pretty decent open source emulators exist that can run older versions, like all the way back to MacOS 7. It can't be that hard to keep the pilot light on for those old things.

You just can’t imagine my lost from not being able to use my 7 device deep SCSI chain including my Zip and Jaz drive

It's a product choice. If you want long-term backwards compatibility, Windows is probably the best option, perhaps the Win32 API on Linux via WINE. Overall, backwards compatibility is a drag on future development. In general, I prefer to drop it myself unless that's the crucial feature. In this case, I'd say I'd make the same choice. Those last few bps of users can simply remain on old software/hardware.