One thing in the story is that the SPU - the secure enclave on Qualcomm chips that is separate from just running on TrustZone on the main processor - is only available on Snapdragon 8 and X tier products. It's market segmented away from 7 series and below.

Also, I think Qualcomm has only started supporting MTE on Snapdragon 8 Elite Gen 5. Older and cheaper SoCs do not support it yet. Outside that, I think only Google Tensor, recent Exynos generations, and Apple A-series support MTE (though IIRC Apple has an improved extension of it).