Apple is the least interesting company to compare against. They are in their own MacOS/iOS software ecosystem, which you want if you want and you don’t if you don’t. Not to be dismissive of either side of that, there are legit reasons to stay in or out of Apple’s ecosystem. But benchmarking points is not a reason anyone would switch operating systems, right?
What OS will these chips run and what is the competition on that platform? He makes a lot of comparisons to AMD and Intel in the post, why not benchmark against them?
Not at all. I specifically bought a MacBook Air M4, first Mac product in my life, for its fantastic performance in a passively cooled notebook. I have zero loyalty to Apple and usually use Windows. If someone else starts beating them perf wise, I'll happily switch again.
Daniel Lemire specialises in high-performance algorithm implementation. In recent years he has been impressed by specific performance characteristics of Apple's CPUs. For example, their ability to eek out the maximum possible throughput from a given instruction stream's data dependencies. My information may be stale, but when I read Daniel's comments I assume that Apple is being used for compariosn because it is the current leader, and take it as given that AMD and Intel are behind. You can probably find sources where he makes head-to-head comparisons with AMD and Intel. If you're not familiar with his work I can recommend it. The Wookash podcast interview is a gentle introduction, there is open source code and academic papers if that's more your thing.
What OS will these chips run and what is the competition on that platform? He makes a lot of comparisons to AMD and Intel in the post, why not benchmark against them?