Pomu is just a lot like Ina'nis. They're not UNpopular, but they're the least popular in their respective branches because they're the most mellow streamers and apparently that's not the kind of thing that the average stream watcher gravitates towards. It makes sense, every time I would take a look at human streamers I would see that the most popular ones were dudes screaming like maniacs all the time. So the mellow ones are perfect for people like me, and I'm glad they're decently popular and have other loyal fans who support them heavily, but I'm not surprised they're less popular than their screaming comrades.

I would contend this logic extends to HoloID as well, I don't really watch Anya that often but I can see she's the mellowest one there and as such is the least popular. I'm sure there are other examples of this in other agencies and such that I'm less familiar with.