Central Governance in Ethereum

Hello. I’m reading the book “Out of the Ether” now and it’s talking about the theft of eth back in 2015, and the decision of Buterin and others about whether or not to create a hard fork and erase the whole history and create a new ledger, or to use some other solution. I’m not finished reading yet, but what I am getting out of this is that the Ethereum blockchain can be controlled by a small group, which indicates it might not be so centralized. Decentralization to me is not the main attraction of digital currencies anyway, but I wanted to ask if it’s true that this means ethereum isn’t really decentralized and whether or not this is an issue. Thanks.