The “Apple only does X better because they do Y” thing has been a meme for ages. I remember dismissals like “PowerPC is only faster at math because it has more integer units” or something along those lines, and thinking, uh, isn’t that a good thing?
This distinction doesn't change what the performance numbers look like today, but it does inform what changes would be necessary for those numbers to look different tomorrow. E.g. Apple Silicon isn't fundamentally orders of magnitude more efficient than x86, they just used smaller features. Newer Intel and AMD chips made on equivalent processes _also_ get similar efficiency gains.
And honestly, they have historically had different markets.
When the design is for only one customer, you don't need to generalize things, and those things you generalize to give different customers different options has costs.
AMD will soon be a larger customer for TSMC than Apple (NVIDIA is already there) so Apple's pre-booking new processes is likely to be gone in the near future.
If I get 10% more performance for 50% more cost it really depends on one's needs, for example.