Agree Apple should reverse course wrt their control freakery. When I bought my PowerBook in 2003, Mac OS (10.3, 10.4) was fantastic in this regard, being able t

Agree Apple should reverse course wrt their control freakery. When I bought my PowerBook in 2003, Mac OS (10.3, 10.4) was fantastic in this regard, being able to boot off a FireWire drive, with OpenFirmware a much more powerful boot loader compared to the archaic pre-UEFI PC BIOS. You could also just use another Mac's boot disk. Today (well, for years now), Mac OS can only be upgraded with Apple's installer. Went to an Apple reseller to buy a hard-disk with Mac OS (Mojave or earlier) to test-upgrade my old Mac Mini and whether my somewhat involved builds still work, only to find out that the old Mac Mini's firmware can't boot from APFS, and a firmware upgrade for APFS isn't a separate download like it used to be but comes only as part of Apple's monolithic online install. This is very significant for delivering/testing Mac OS apps on newer OSes, and in particular to F/OSS developers who can't always go with the program and buy new hardware all the time. It's also relevant with audio and video professionals who need their driver- and timing-sensitive rig to work rather than going through yearly upgrade treadmills.