[slgeorge]

I think you know this as you mention "olden way" - it's definitely the thread of history where most UNIX servers were multi-user systems: that's how I was first exposed to Unix, even though by late 80's/early 90's most of them were Linux or a *BSD. In those - presumably University mostly - environments, we mostly sent email to each other and that was often between servers on a campus or environment. It made sense then that each server sent email because you were specifically [e-mail].

When the distros started to expand, being a smarthost was the most common configuration. Today, I agree with you the only reason for any sort of SMTP daemon is for programs to send email - all the users are on Google/Slack.