I figure that people work so hard these days in maximizing the number and breadth of nominations (like with the posts and spreadsheets where people collectively share their nominations so they don't duplicate or whatever) that they had to put a rein on it somehow. Or at least that's what I assume.

I hadn't thought about it before, but I guess I nominate more with an eye toward writing than reading, because there are so many more things I can read with pleasure than I feel I can write to order. I need to make 100% sure there are enough fandoms I can safely and productively offer, whereas there are always enough that I'd enjoy receiving even if I didn't nominate anything.