This is really on the low end of effort required. They don't need to create anything, just document what's already there.
I think a web team would need to create an entirely new backend, yeah? That can pull from an API that would also need to be built? Plus localizing all versions of that site and ensuring the right regions get the right calls, etc.
At the very very least it's a web design overhaul, which is not a small task. If the choice is to manually enter the data, ie using what is already there, you then have a LOT of old data to port and a LOT of checks and balances to ensure it stays updated.
I'm not saying it's the hardest task on earth (I imagine Riot's engineers solve a lot harder problems on the daily), but it's also not super simple.