My gopher hole is hosted on a single server, and to access it, everyone has to connect to it. This is opposed to the concept of decentralization you can have in IPFS for example, where I would publish a phlog entry directly from my computer, and you'd connect directly to my computer to get it. Then we have two copies on the network (yours and mine), so anyone can grab either of this copies to retrieve it. It's decentralized in the sense that you are not forced to grab the content from a central place.

Note that centralization isn't bad per se. Gopher is centralized, it's a fact, but it's not necessarily bad. For stuff like payment, relying on a central place isn't ideal though because you must rely and trust a 3rd party to handle your money.