Thank you very much for this reply to my question, and it's an important point you make.

I agree that if someone doesn't clean them regularly, as directed, then, they might likely grow mold inside them, and spew it around the breathing space, rather directly.
I was also and more curious, though, about whether one should also, on an ongoing and regular, continual basis, be monitoring the levels of their own room humidity,
to be certain one doesn't use it too much, and so much that would cause the normal molds already in your air space,
to grow and reproduce extremely more rapidly and exponentially, than under normal conditions without any humidifier.
I don't know, but it seems likely to me.