Whilst your premise is correct, don’t forget the 52CU Series X is 4K (approx 8 million pixels) and the Series S with its 20CU is 1440p (approx 4 million pixels).
With just that simple fact the S would only need 26 CU to equal the X, and that’s doesn’t consider the exponential load increase as resolution rises for things like ray tracing and other shader effects.
As the article said, better to compare it to the One S which has 1.4 or approx half the power of series s once you take higher resolution and new effects etc into account
I know from testing PC GPUs that going from 1440p to 4K (2.25X as many pixels) typically drops performance around 40% (provided you don't run out of VRAM). RTX 2080 Ti averages 122.6 fps at 1440p ultra and 164.5 fps at 1440p medium across eight games; it drops to 73.4 fps at 4K ultra and 98.0 fps at 4K medium. So that's 40.1% slower at ultra and 40.4% slower at medium. The 2080 Super (which is slightly more GPU bound) gets 143.7 fps at 1440p medium and 82.8 at 4K medium (42.4% slower), and 106.1 fps at 1440p ultra vs. 61.8 fps at 4K ultra (41.8% slower). Or if you prefer the reverse, 1440p runs 70-75% faster than 4K.
That's keeping the GPU performance completely the same. But the problem is that the Xbox Series X/S isn't even remotely the same on the GPU front. Going from 52 CUs at 1.825 GHz (12.15 TFLOPS) to 20 CUs at 1.565 GHz (4 TFLOPS) is a massive drop. It's also 10GB of VRAM for the GPU with 560 GB/s bandwidth to 8GB of VRAM with 224 GB/s, and 6GB vs 2GB for the system.
I think the Xbox Series S will still perform okay, but it looks much more like a 1080p 60 fps gaming system that will become outdated very quickly. Unless MS has game devs actually change other settings besides resolution? That could work, but I'm not sure console gamers will like it if they discover the $300 version not only can't run as fast, but also looks worse while running slower.
Nvidia just announced GPUs with 20 to as much as 36 TFLOPS. Even if the real-world usable TFLOPS is more like 14 to 25 (and it is, relative to Turing), that's still a big difference. And a big difference in price, obviously, but the Xbox Series S isn't even going to match an RTX 2060. Maybe that's a better comparison of what I was hoping to see.
RTX 2060 is a $300 GPU, RTX 2070 Super is a $500 GPU. The 2060 is 25-30% slower for that price drop, not potentially 66% slower.