Why are holes needed for the finer grating of cheese?

I use the tiny holes for zesting and nutmeg.
On cheese, never.

I think the microplane rasps are the ideal tools for grating dry cheeses. They let the shavings pass through, so they don’t collect between the cheese and the grater and get compacted as you continue to grate.

I use them on very hard dry cheeses that I want slightly more shred than dust. That said, unless the weather is really bad, you need to go outside. ;-)

The holes are there so the cheese does not clump up.

Romano is hard and flaky. Mozzarella isn’t, and would turn to mush rather than tiny pieces.

Romano is easier to do that with than a moist cheese, a more moist cheese, like mozarella, or even mild cheddar, may not flake off as nicely.

@marinelife explains the whole question very succinctly! Soft cheese clogs up the small openings.