> There is a whole lot that SSH can do that most people don't know about.

I had to port ssh to embedded hardware decades ago, and pulling back the curtains I came to the opinion that everything was a mess.

for example, I needed to be able to upload/download firmware, and was surprised to find that scp wasn't a pure file transfer protocol. It is more like "log into the remote system via shell and run a file transfer program"

There are lots of other things I didn't like, like wholesale transferring environment variables back and forth, weird shell interactions and more.

It is very useful, but it is an organically grown program, not a designed protocol.

Scp not needing its own protocol is a feature and not a bug in my book..