Probably the same reason why only newer than 8000 series Intel CPUs are officially supported for Windows 11.
It's the "easiest" way to ensure TPM 2.0 compatibility, at a CPU family level of granularity. (Yes, there are 7000 series with TPM 2.0 support, but I believe that may have been the exception to the rule)
Edit: I took a look at the certified list and noticed that I indeed, cannot read.
