> If the bombs drop and civilization is over and me, and my home lab are the only survivors, can I still use that software?
which rules out any software used to connect to non existant other servers or people.
Sure, the software "works" .. it just doesn't do anything .. ie. it can't be "used".
That ircd servers in the example above can still be used with a bot as an automation tool (at that point as the only survivor the security would be the least of your concerns), as a way to invent imaginary friends to pretend your life is less miserable, whatever.
Or say you have a mastodon or pixelfed instance. Sure no other instance will ever connect and no other user will ever be able to see your posts...but you. Which could include some fond memories you want to keep.
These semantic games are obfuscating the real issue here; tying the definition of "self hosting" to the "If the bombs drop and civilization is over and me, and my home lab are the only survivors" scenario is less useful than a two handed pit saw to a sole survivor.
I appreciate your assist to what I consider to be fragmede's "foot in keyboard" moment of poor definition, I suspect we're all better served with a better definition.