I wouldn't say that Ethereum is fully decentralized. Only partially perhaps. There is this developer team with an uknown premined stash, who decides what to do with the bloockchain. This is done without asking the users, including reversing transactions in case they don't like something. This is what happened in 2016, after the DAO accident. Since then the project has been compromised and nobody can state that it is truly decentralized. Now we see a switch from POW, which was the only decentralized element, to a POS, which is like the fiat money. So with time instead of going more decentralized, ethereum is going even less decentralized. It is like a fiat money blockchain, which allows ponzis to be made on top of it, like DAO, Icos, Defi, etc. So everyone investing in ethereum must know, that they are trusting their money to a team that makes all decisions on their own and may split and abandon the project anytime. One of the inventors has already left the project. And finally, nobody knows what is the supply and what it will be after the POS switch. So it is not about bitcoin maximalism as Vitalik is trying to defend his project. This is the truth -  that the only fully decentralized blockchain is bitcoin. There is the Core's team of course, who is changing with time but they always ask the community for each change. The users and miners vote and then the change is implemented. And we are talking about small techical soft forks like segwit and tarpoot, which are expanding the decentralization.