I thought it was a good read, although with a couple of mistakes and a somewhat (IMO) childish sense of entitlement. This reads a bit like something a young teen who is heavy into tech wrote. I'm sure I could have authored something with the same overall tone and vibe when I was younger (perhaps not same quality, though!). Either way, it's a very decent read!
The idea that YCbCr is only here because of "legacy reasons", and that we only we discard half of chrominance because of equally "legacy reasons" is bonkers, though.
The core idea of YCbCr - decoupling chrominance and luminance information - definitely has merit, but the fact that we are still using YCbCr specifically is definitely for historical reasons. BT.601 comes directly from analog television. If you want to truly decouple chrominance from luminance, there are better color spaces (opponent color spaces or ICtCp, depending on your use case) you could choose.
Similarly, chroma subsampling is motivated by psychovisual aspects, but I truly believe that enforcing it on a format level is just no longer necessary. Modern video encoders are much better at encoding low-frequency content at high resolutions than they used to be, so keeping chroma at full resolution with a lower bitrate would get you very similar quality but give much more freedom to the encoder (not to mention getting rid of all the headaches regarding chroma location and having to up- and downscale chroma whenever needing to process something in RGB).
Regarding the tone of the article, I address that in my top-level comment here.
I would have also expected at least a passing mention of chroma subsampling beyond 4:2:0 if only just to have an excuse to give the "4:2:0" label to the usual case they mention. And you might run across stuff in 4:2:2 or 4:4:4 not all that rarely.
The idea that YCbCr is only here because of "legacy reasons", and that we only we discard half of chrominance because of equally "legacy reasons" is bonkers, though.