Because then only people with Intel Macs care. People like me, who remember the 2019 i9 Macbook Pro being one of Apple's least-recommended laptops, are kinda unfazed by favorable performance comparisons. There are probably hundreds of laptops that can destroy it in a fraction of it's power envelope; it wasn't a great machine.

Mostly, it's ironic that Apple is comparing themselves to a company that they want so desperately to escape. And, once you do run the math on their actual year-over-year improvements, it's not that different from AMD or Intel. And Apple is increasing their power consumption to hit those numbers. It's quite literally square one in a sense, just with a different CPU architecture and a different manufacturer.