I guess the real question would be; why do muhjoos show up in the middle of the night when everyone has gone to sleep? What purpose do they serve spamming a board no one will pay attention to for hours? They don't even feel like they're here to convince anyone, just talk long enough to keep things going until the organic traffic starts again. But speak to them and you can tell at least a few of them aren't bots, they're real people who show up at certain times to talk in circles while everyone's asleep.

Maybe I'm giving them too much credit, but you notice patterns over the years and they're almost too predictable at this point.