It may also help to realize that just because the people logged in are not readily accessible or out in public, doesn't mean that they aren't contributing to the game's activity. Are some people just sitting around? Sure, probably most (though people may be doing that in public as well). Are some waiting to connect with someone OOC so they can arrange deets of events, meetups, prps, ect? Yes. Esp. if they do not have large chunks of time during the day, and so need to coordinate (or even extreme slow play) during that time so they are better set up for the more active/present time that they do have. In that respect, they may be contributing "more" to the game and activity for others than someone who just hangs around in public all the time and pounces on BaRP but never runs anything for anyone or a group of folks, depending on your perspective.
People are not going to go out in public to extreme slow RP (and that's going to look like idling too) that's disrespectful to people who might wander in and people get angry about when people don't pose fast enough for their tastes as well.
I think I personally have a reaction to compulsive WHO and +where checkers because those tools have been used to harass me/track my activity by people in the past, and so a need to constantly check those things and judge people by them tends to trigger a red flag in me. I can kind of understand wanting that as a metric to judge whether or not a game is worth your time, if it is supremely important to you to have a certain percentage of unidle people or public people. I'm just not sure that even that is useful though, given how people are often very unidle just chatting about the weather and their health issues on channel while never darkening the door of a public scene, and planners may be idle for long times as they're writing up stuff/researching/otherwise actively working towards a contribution to the game.