[Wicher]

I think the use case is ad-hoc, as described on the page. I think the author may know about syslog, but this ad-hoc approach is useful when something such as syslog is not set up correctly and you can't fix it right there and then. This allows you to investigate and fix some bug over the weekend without having to involve others or other bureaucratic domains.

[gushogg-blake]

Yes - basically I encountered all of the example situations on the page and knocked up the initial version in a day or so (originally for the "PHP API" scenario specifically). I did add some extra features like setting your own namespace/logging key and controlling visibility, but in the end they didn't really match the use case - "one person doing ad hoc debugging in an unfamiliar environment" - so I stripped them out.