It's because it does just one thing, and it's doing it VERY WELL, as a decentralized, censorship-resistant cryptocurrency that can be used as a Store of Value and a Medium of Exchange. All those other blockchains with "many features" are a Rube Goldberg Machine, that overcomplicate solutions instead of simplifying them.

"Cryptocurrency Number 2" is the biggest Rube Goldberg Machine. Jimmy Song explained it in his blog, https://jimmysong.substack.com/p/ethereum-is-a-rube-goldberg-machine