Using the Wayback Machine for SEO
https://searchengineland.com/5-ways-to-use-the-wayback-machine-for-seo-383754
The Wayback Machine is an internet treasure. And it turns out you can use it for SEO. Just found this article on how to do it — worth a read. TL;DR: Use it to spy on what your competitors are doing.
It's also a great tool if you want to acquire another business.
Interesting point!
I've actually done this — would recommend. But only when you have something specific that you want to figure out. I doubt it would be that productive to go analyzing years' worth of changes on a competitor's site unless you've got a lot of time on your hands.