The failure to mention GNU Social, which Mastodon is almost completely based upon and which birthed the Fediverse, is just weird.
GNU Social is made in PHP and Mastodon is made with Ruby and NodeJS. So two wildly different implementations.
Mastodon also looked more modern and followed more so called modern developing practices. Which is why I think it caught on more than GNU Social ever did.
I tried GNU Social a long time ago, but it was mostly technical people talking about technical stuff. Great if that's what you're into, but it's no basis for a general use social network. Niche networks are fine, but I don't get the impression that's what early federated social media proponents wanted.