This is just a low quality ad for some guy's substack, and to like & follow him. It's too bad to see it ranking highly
If someone publishes original content for free and in the end puts a link to their paid blog, I really don't mind it. I've seen far worse advertising.
It explains and illustrates a fact beautifully. You're not meant to be able to do the calculation yourself if you found yourself back in time
Plus I found the read fairly interesting.