Yup, the only reason Macs have higher memory bandwidth is because they use more memory channels, which gives them a wider bus. Both Intel and AMD only allow more than dual channel memory on server class processors these days.
The memory bandwidth is a small thing compared to the massive win you get by not having to move data between two memory pools at all.
Threadripper have that extra bandwidth and M5 still is faster
Except strix halo.
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?