Guy built custom computer but ran Windows 10 on a MBR disk with legacy boot (BIOS/CSM) and TPM disabled. Ran 11 compatibility check and was surprised that Windows 11 won't work with that.
Also advocating that MS sells a version that relaxes this requirement (AFAIK - Windows will run on the system anyway but support people may* turn you away and your system will be less secure). For reference, the insider preview build works just fine on my 7700k system with TPM disabled.