This isn't a list of shoulds. It's a list of, generally dones. Big difference.

This one is still nowhere near universal enough to count in the original lisr sadly.

This is probably technically out of scope for this article. Long-running processes that respond to SIGHUP will usually be running detached (with no controlling TTY). Thus it is a bit of stretch to call them "terminal programs".

This behavior seems difficult to actually implement in practice, no? Your application has to be careful not to accidentally cache any configuration state, as well as any state derived from the configuration, otherwise it will go out of sync. Maybe easy for trivial apps but most apps requiring configuration files are non trivial.