I don't know if it's a question of severity. I think it's more that some people respond really well to meds and some people don't. Someone with "super huge severe" bipolar could do really great on meds, and someone with "less severe" symptoms could not respond to meds at all and need a more holistic approach. And some people need to blend the two.

Things get tricky when you start applying severity or high/low functioning labels. We each live our own life, and since other peoples' realities can be wildly different from ours, how do we really know who is the most severe?