Decentralization is a fiction. And evil.
1. Developer access. The forkings (aka, developer changes) show that a small group of people could have their loved ones kidnapped or threatened and be forced to change the code.
2. China manufactures ~95% of PoW mining rigs and mines 66% of all BTC and about the same for all the other major coins. China has outlawed transacting in crypto and even having an account on an exchange. Go figure.
3. Currently, the overwhelming majority of transactions originate off the chain(s).
4. And this: https://www.cs.cornell.edu/~ie53/publications/btcProcFC.pdf
5. Decentralization is the belief that all government control of money (or other things) is bad. Imagine a world where there was no way to economically sanction a holocaust. Kind of already happening in a variety of countries where crypto is the dominant store of value for the country's (klepto/authoritarian) governments.
Yay freedom... from ethics and good government.