I feel need to address some points of the authors (I realize it's a hot take so it's meant to be biased): > But what does this buy us? For the most part it mea

I feel need to address some points of the authors (I realize it's a hot take so it's meant to be biased): > But what does this buy us? For the most part it means that every piece of content everyone writes needs to be replicated to every point in the federation mesh to be useful. This is because ActivityPub is tied to RDF and linked data concepts. This isn't specific to ActivityPub, just a criticism of the linked data web. As we will see later, the author doesn't quite understand that linked data can be fetched only on demand and represented otherwise as only an IRI, reducing data replication to a minimum. It depends on the specific ActivityPub implementation. > This isn’t creating a distributed network, this is creating a whole bunch of massive points of failure. This is a pretty ungenerous characterization. It's a distributed system where robustness is not a part of the protocol. It needs to be solved elsewhere, so innovation is needed. > Meanwhile, what does this buy you? Immediacy of updates? Okay, does it really matter how quickly you see someone’s new content, if it’s worth seeing? I think this is another ungenerous characterization. It buys a federated set of communities and applications that can exchange linked data in real time. > For example, user-agents and RSS providers can use the If-Modified-Since: header to only get the feed updates if the content has changed since the last fetch. ActivityPub also has a diffing system of data in place with Update activities too. > Oh, and ActivityPub stuff generally also means that all attachments and other content also get replicated. This is not true and is entirely implementation specific. If Mastodon creates local caches of federated data, that's it's design choice. Other applications can always fetch-on-demand and go back to the Pull Model. That being said, static sites are not served by ActivityPub so that portion of criticism is definitely spot on.