I think if you host an event, a party, a gathering, etc. You hold some responsibility over the impacts of that event both positive and negative. If it’s an awesome success, great! You hosting that event are partially responsible for that success. If it causes many issues and requires a cleanup, you also hold some responsibility for that.
I think hosts of events that use iNaturalist that do not engage or help at all if their events cause large issues should be suspended / blocked from creating future projects if all attempts to communicate with them after months fail.
Again, when you host an event, say a gathering at a house. You take partial responsibility for the event and even actions of the people you invite. While the analogy isn’t 1 to 1. I fully believe that hosts are partially responsible for the content participants of their events upload.
Does this mean the burden fully rests on the host? No and it shouldn’t, but if there are issues, especially widespread major issues with the contents being uploaded from your event. You need to show some responsibility for that.