Hm... how to explain...

First, in case we really pay, several people are more expensive - either directly in money or indirectly in time they need to coordinate themselves.

Then: How would you split it up?

In case of the coordinator he can split up work to volunteers. After all, he should not stop people from contributing.
But for that and knowing what needs to be done you need a list done by someone who knows the stuff.

In case of one person, if he goes MIA you have the list and, because of the reports, a nearly up to date point f where to take up the work.
Several people again it is harder to tell if MIA and harder to take up the loose threads.