> Previously you always could install the newer Windows. It might be slow, but it'd work.

Windows has always had published minimum requirements and actual minimim requirements.

A 286 will run Windows 3, but not Windows 95 or NT.

A 486 will run Windows 2000 slowly, but I'm pretty sure you need a Pentium for XP (wikipedia says Pentium 233 Mhz).

There's plenty of examples of increased requirements over time. The TPM requirement may be different in character, as it's simple to bypass and Windows 11 then reportedly runs fine, but it's certainly prescendented that some equipment that ran the old version can't run the new version.