It may seem contradictory that all these ‘decentralised’ protocols are based on a very centralised structure such as the DNS, when one could use a DHT, like torrent is doing.

Ah there we go. So it’s about how AP is not peer-to-peer and not DHT based, I guess. Well, SecureScuttleButt is right there Also, “decentralized” doesn’t exclusively mean “peer-to-peer”.

Could SMTP, XMPP, SIP have been used to build the fediverse? The answer is: yes, and they would have worked MUCH better. How do I know? Because they are widely used, and they DO work much better. As easy as that.

If they all work so well and all can replace ActivityPub, can’t they replace one another? In that case, why do we even need SIP and XMPP if SMTP was there and already popular?

The answer is: because these are old protocols that are a hell to implement, and were done in completely different times with completely different threat models and for completely different purpose.

This is not a technical assessment, meaning: if all three protocols (plus ActivityPub) can succeed in getting a message to a user (using MIME for SMTP, SDP for SIP, and XML for XMPP), they are all equivalent. If all of three can do it while also describing the type of message , they are equivalent.

Okay, so what exactly is the author saying? “They all could replace ActivityPub, but not really actually”?

Still we must admit that some aforementioned protocols [SMTP, XMPP, SIP] have created huge ecosystems and hundreds of applications, while ActivityPub seems to be relegated to a very few applications aimed at mimicking GAFAM, and nothing more.

Perhaps that’s because the oldest of them had ~40 year head-start, and the youngest (XMPP) over 15-year head-start over ActivityPub.

The only actually reasonable criticism of ActivityPub I see there is the documentation and implementation bit. AP’s documentation is, indeed, not amazing, and implementing it requires testing stuff out regarding how other AP-implementing software does things.

Which is both true, and interesting in the context of pointing to XMPP as a “better” protocol (ermahgerd the XEPs…).

I don’t know why the person is so bitter, but I hope they get better.