This is a reference to the 51% problem, which is one of the fatal flaws of existing blockchains, but is rarely brought up as a criticism due to its unlikelihood of mattering for any major blockchain.
What it comes down to is this. Let’s say I have 0 bitcoins. However, I somehow get an extremely massive number of computers under my control. I have so many computers doing mining that of all the computing power in the world dedicated to the bitcoin blockchain, I control 51% of that computing capacity.
At this point I now completely control which transactions count as valid and invalid. I can create whatever transaction I like, and it will happen. I can just create a billion bitcoins for myself. I can transfer everyone’s bitcoins to me leaving them all with zero.
You can see this is very unlikely to ever happen for any blockchain with lots of users like eth or btc. It’s not even a concern. It is a huge concern for unpopular coins as someone with a bunch of money and/or computers can just take it over.
As the article correctly points out, that is the opposite of decentralization. There is one true authority, the consensus formed by 51% of the votes. Everyone else must fall in line with it. True decentralization consists of independent nodes all operating as they please.
Email is truly decentralized. Every email server is its own boss. Sure enough there are lots of standards and protocols surrounding email, but nobody forced anyone to behave a certain way. You can disobey the protocol. Every other node will independently decide how to handle your misbehavior. If one email server likes spam and wants to deliver it to its users, they can do that. If an email server is ok sending out piles of spam, they can do that if they want. If GMail decides to block all mail coming from your mail server, even if you follow all the rules and never send spam, they can do that too. Everyone does whatever the heck they want, but those who cooperate naturally end up providing valuable services, and those who don’t, don’t. No centralized authority, be it a single entity or group of entities, exists.
Neither autocracy or democracy, decentralization is anarchy.
