They stopped selling the last Mac Pro and mac mini 3 years ago.. So literally, their top end computer had 3 years of support of the latest OS (if you bought at the end of the cycle). And, they pulled this same BS from PPC to Intel, so, its not the first rug pull. And, its not like Windows hasn't maintained excellent backwards compatibility otherwise (they still offer windows 95 backwards compatibility in a lot of cases in the latest OS). In fact, if your computer supports it, you also got a free upgrade to Windows 11 .
In this case, the Intel Macs include a T2 chip, so, its not like there is a valid security reason to break MacOS.. They literally just blatantly screwed them (the Mac Pro was NOT a cheap computer).
Coincidenally, MacOS 27 beta breaks Linux too. https://www.phoronix.com/news/macOS-27-Beta-Breaks-Asahi .