here you have Authenticated Transfer Protocol. you can get data very easily. via any of a huge range of means & sources! we have some examples ones today (direct from a pds, relay, jetstream, appview, new protocols like Atom (atproto over MoQ), new systems like hubble). and in most cases, you can tell that it's from a certain account!

i agree with you, i just think the bases are mostly covered here. i also think that it's a fascinating topic. and yes it matters. an "Atproto for Distributed Systems Engineers" probably should know why atproto has such great addressable data (not hash based though), signed key crypto. but also, if you dig in, you'll find quickly it has a great story here. (although your https://anproto.com/ indicates some clear disagreement about sufficiency.)

and the higher level what it is and how it works here is a much more useful practical guide, for getting started with.

there's a lot of people who focus on distributed, on what that means. what seems a lot missing though is that atproto is already nicely a nicely authenticated (crypto) transfer protocol. and that it's probably the best actually distributed, in terms of data availability, in terms of people trying to get your data.