It is not new. I downloaded (copyrighted) porn movies from my ISP's own Usenet servers in the early 90s. On dialup. It was a decentralized, federated service before anybody even knew what decentralization or federation even meant or why they would want it. It was just assumed that everyone would want to run their own Usenet servers because the technologies of the time didn't allow direct, continuous, real-time connection between everybody. Sharing was expensive but running a Usenet server was relatively cheap and was a good way to share all that data to all of an ISP's users at once. It was ALWAYS an option to use it for piracy, and people did.
Nowadays, sharing is cheap, and running Usenet servers is expensive, so almost nobody runs their own Usenet servers, especially not ISPs. But that's not the technology's fault, it's just the way the world has changed. The internet is a very different place now, and we use it in different ways. Usenet, on the other hand, has not changed at all. Only the people using it have changed.
...is this process not against the spirit of piracy
It could be against the anti-establishment values of some digital pirates, but it's not at odds with the nature of piracy itself.
Piracy on the internet is just distributing digital goods protected by intellectual property law without the permission of the copyright holder. Some pirates engage in this practice for political reasons, but for many others it's simply a matter of economics or availability.
Usenet is older than torrenting. Significantly older. Even older than the WWW IIRC... Every few years the newer generation "discovers it" and realizes you can totally saturate your connection, even with relatively obscure things that would typically need a significant number of seeds to be able to do.
And then it falls to the wayside again, because retention times kinda suck as no one wants to keep petabytes of data for ultra-long term. That and most of the indexers still alive today fucking suck.
I think your confusion is in thinking that Usenet is a centralized space. It isn't. Yes, you need a provider, but if one does carry what you want, you go elsewhere.
Highly recommend reading the wiki articlenon Usenet.
I found about Usenet and the sort of “hype” relative to it and I wonder some stuff.
Usenet's been around in its current form since 1987! The problem for pirates is finding decent providers who serve binaries. I used to use Easynews as they had great retention and they seem to still be around.
Usenet is decentralised, but - as mentioned elsewhere - relies on a handful of providers to service the binary groups.
usenet is decentralized at server level. In theory all the servers have the same content. Currently everything is obfuscated because of the take downs - so you need an indexer (the users upload the nzbs to that website. Think of a nzb like a .torrent file.)