The simple fact that an M3 Ultra system with twice as many cores, some hellacious main memory speed (as long as the GPU's not too busy), etc. only sees 25-30% performance a is a testament to the wisdom of AMD maintaining multi threading. How about a core to core test? Or a price to price test? Why claim these AMD and Intel chips are peak, when there are Threadrippers, Threadrippers Pro, Xeons, and Epyx processors... Some well in the same price range as an M3 Ultra system.
Sure, the M3 Ultra will use less power. But both systems are plugged in. The power efficiency in a laptop matters, but every laptop is an inherent cost, performance, and usability disadvantage.