It is a mystery. All I know is that generations of possums have been raised in my blocked off fireplace without drowning, and there is no sign of any moisture coming from the fireplace to the inside of the house. At this point I’m just assuming there is an invisible force field that keeps rain out but not possums.
It would be nice if you could have more than one category of bot. There is a huge difference between a bot which makes regular posts like daily threads which are part of the organisational structure of a group and bots which crawl through content to make replies, reposts etc. Even just a difference between general bots and ones which are also moderators of the group would help.
I chose to not label the bot I use to create daily posts, not because I want to stop people being able to filter it out (if they want to they can just block the bot easily enough), but because I don’t want to remove the ability of people in my group to filter other bots. Given that the group consists almost entirely of chat in automatically posted daily threads by marking the bot as a bot I would be effectively forcing people to chose between participating in the group and blocking more general bots.