I didn’t realize bluesky was even described as decentralized til recently.

Well I agree with this:

There is one other thing which Bluesky gets right, and which the present-day fediverse does not. This is that Bluesky uses content-addressed content, so that content can survive if a node goes down. In this way (well, also allegedly with identity, but I will critique that part because it has several problems), Bluesky achieves its “credible exit” (Bluesky’s own term, by the way) in that the main node or individual hosts could go down, posts can continue to be referenced. This is possible to also do on the fediverse, but is not done presently; today, a fediverse user has to worry a lot about a node going down. indeed I intentionally fought for and left open the possibility within ActivityPub of adding content-addressed posts, and several years ago I wrote a demo of how to combine content addressing with ActivityPub. But nonetheless, even though such a thing is spec-compatible with ActivityPub, content-addressing is not done today on ActivityPub, and is done on Bluesky.

Later on she describes how it costs thousands if not 10s of thousands USD to run a server that doesn’t even do everything

Now, you may see people say, running an ATProto node is fairly cheap! And this is because comparatively speaking, running a Personal Data Store is fairly cheap, because running a Personal Data Store is more akin to running a blog. But social networks are much more interactive than blogs, and in this way the rest of Bluesky’s architecture is a lot more involved than a search engine: users expect real-time notifications and interactivity with other users. This is where the real architecture of Bluesky/ATProto comes in: Relays and AppViews.

So how challenging is it to run those? In July 2024, running a Relay on ATProto already required 1 terabyte of storage. But more alarmingly, just a four months later in November 2024, running a relay now requires approximately 5 terabytes of storage. That is a nearly 5x increase in just four months, and my guess is that by next month, we’ll see that doubled to at least ten terabytes due to the massive switchover to Bluesky which has happened post-election. As Bluesky grows in popularity, so does the rate of growth of the expected resources to host a meaningfully participating node.

Bluesky is actually like usenet:

Bluesky does not utilize message passing, and instead operates in what I call a shared heap architecture. In a shared heap architecture, instead of delivering mail to someone’s house (or, in a client-to-server architecture as most non p2p mailing lists are, at least their apartment’s mail room), letters which may be interesting all are dumped at a post office (called a “relay”) directly.

I don’t understand the credible exit idea.

Even though the majority of Bluesky services are currently operated by a single company, we nevertheless consider the system to be decentralized because it provides credible exit: if Bluesky Social PBC goes out of business or loses users’ trust, other providers can step in to provide an equivalent service using the same dataset and the same protocols. – Bluesky and the AT Protocol: Usable Decentralized Social Media

It is not a bad choice for Bluesky to be focused on providing an alternative to X-Twitter for those who miss Twitter-of-yore and are immediately looking for an offboarding from an abusive environment. I understand and support this effort! Bluesky does use several decentralization tricks which may lend themselves more towards its self-stated goal of “credible exit”. But these do not make Bluesky decentralized, which it is not within any reasonable metric of the power dynamics we have of decentralized protocols which exist today, and it does not use federation in any way that resembles the way that technical term has been used within decentralized social networking efforts. (I have heard the term “federation-washing” used to describe the goalpost-moving involved here, and I’m sympathetic to that phrase personally.)

In my opinion, this should actually be the way Bluesky brands itself, which I believe would be more honest: an open architecture (that’s fair to say!) with the possibility of credible exit. This would be more accurate and reflect better what is provided to users.

This article is about 10k words and I’m 2/3 through it.