Since others starting intercepting and eavesdrop on non-authenticated traffic, it got a lot less comfy to do so though. It's not like people are adding encryption to stuff for the fun of it.
it seems the parent comment isn't referring directly to encryption / TLS, but building everything on top of HTTP / HTTPS, which seems to be the default abstraction these days to build on top of.
I agree, it is always HTTP nowadays. The Librecast project [0] is doing interesting R&D around multicast and social networking, and has been / is being funded by multiple NLnet grants over the years. I think they have plans to use ActivityPub to demonstrate their work. Current active project is LibreCast Studio, a collaboration environment. The linked video on the page is a very interesting watch.
Of course not, the context here is ATProto which literally stands for "Authenticated Transfer Protocol", and it uses other protocols than just http/tls, so of course there are other ways :)
In addition to the middlebox problem, most (not all, but most) of the things that send information over the Internet that aren't HTTP-shaped (incl. HTTP/2 and HTTP/3) are worse than the best HTTP-shaped things. This makes sense: HTTP-shaped things are where all the energy is directed.