Steve Bellovin wrote a great series of articles describing the early history of Usenet. The most interesting part in the “security and authentication” part was probably this gem:

That left us with no good choices. The infrastructure for a cryptographic solution was lacking. The uux command rendered illusory any attempts at security via the Usenet programs themselves. We chose to do nothing. That is, we did not implement fake security that would give people the illusion of protection but not the reality.

A lot of other early implementers chose the same route, resulting in SMTP, BGP… which wouldn’t be a problem if someone kept track of that and implemented security a few years later. Unfortunately we considered those problems solved and moved on to chase other squirrels. We’re still paying the interest on that technical debt.