Interestingly, the software giant added this check since the Windows 11 24H2 will not boot without these instruction sets, according to a previous report. Though speculative, one would wonder if the company has this extra step in case someone uses bypasses to force the OS to boot with an unsupported CPU.
Only targeting new hardware is just a win-win-win for them.
Hardware partners love it, planned obsolescence is just new sales. Legal departments love it, constantly worse DRM. The development teams like it, less support burden. Marketing loves AI being a core feature.
They have no competition. There is no downside for them.