I run a website that's in a similar situation, and it sounds like the author is close to the correct solution, but needs to take things one step further: There needs to be a Single Point of Truth, and it should not be your little website. BigCentralThing should be the official database that knows about where all the Whatevers are. Your little Whatever Locator site should only ever _pull_ from them. Need a new Whateve…
This way you get less contributions.
It's just a matter of dropping a link to that route's page into an importer to scrape it in and have it be usable at our end.
But yeah, for a space where the Big Database didn't often have a record for the things your users want to add, I could see it being more of an issue.