Chatter clients have a chance of making a reasonable determination as to whether someone is present. A good client allows the user to say whether they want the client to make them appear logged in or not and, if it is making their presence known, then it should provide a time-out after which no interaction means that it automatically stops making their presence known.

Perhaps you are thinking that PerlMonks should not count chatter fetches as "presence". We do better than that, we let you pick. I could support making chatter fetches not count as "presence" by default, but then we'd need a way to specify two types of non-default behavior, which will make ;ticker= confusing and introduce a backward compatability problem.

Or we could take away the option to have chatter fetches count as presence, which means that several clients will require enhancements in order to provide features that they already provide and that people want (and will add to site load required to provide that feature).

It isn't hard to "fix" presence processing such that it happens elsewhere and can be overridden many places.

I don't see how to make PerlMonks do a good job of detecting presence. Clients can do a good job of this but most client authors don't bother to and, yes, doing that right varies by client.