Agreed. Also Christof Paar's book [1] and 25-episode YouTube series[2] do an excellent job of explaining not only elliptic curve cryptography, but also RSA and a lot of other cryptography, including symmetric ciphers and cryptographic hash functions.
The blog post seems to be essentially, "I read these good posts on Ars [3] and F5 [4] [5] and here is my summary of my understanding of them". Nothing wrong with that, but the post has some issues and doesn't add anything to the sources cited IMO.
[1] http://www.crypto-textbook.com/ (ironic that https isn't available?!?!)
[2] https://www.youtube.com/channel/UC1usFRN4LCMcfIV7UjHNuQg
[3] https://arstechnica.com/information-technology/2013/10/a-rel...
[4] https://devcentral.f5.com/s/articles/real-cryptography-has-c...
[5] https://youtu.be/dCvB-mhkT0w