This is true, but the M-series is not as impressive as it was when it was first released in November 2020.
Apple may have the edge in performance per watt. But, when looking at high-end computers, performance per dollar is even more important.
Apple charges a premium for its computers. It is fine when Apple sells an M1 MacBook Air for $999, which is faster and lighter than any Windows laptop at the same price point.
Now let us get a high-end desktop. Look at these two configurations:
Mac Studio: Apple M1 Ultra 48-core GPU, 64 GB RAM, 1 TB SSD, USD 3,999.00
PC: Intel Core i9-12900K, GeForce RTX 3090 Ti, 64 GB RAM DDR4-3600, 1 TB NVME SSD, USD 3,700
Mac Studio: Apple M1 Ultra 64-core GPU, 128 GB RAM, 8 TB SSD, USD 7,999.00
PC: Intel Core i9-12900K, GeForce RTX 3090 Ti, 128 GB RAM DDR4-4000, 12 TB (3x 4 TB) NVME SSD, USD 6,000
The PC has a far better video card, and yet is cheaper than the Mac Studio in both scenarios. In the second one, the PC is 25% cheaper, even having a better video card and 50% more storage.
If I were a high-end user that needs a desktop with lots of power, I would probably care more about performance per dollar than performance per watt. Perhaps the forthcoming Mac Pro addresses this issue, but we should check the price tag.