It was explained in the talk at Git-Merge that their problem is not large files per se. The codebase is huge in the amount of source files alone. It was stated that the repo contains about 3.5 million files. Having IPFS here wouldn't help, would it?
The main added benefit is that if your friend on the LAN has also checked out the parts you need you can get them directly from them rather than some central repo, which could make a big difference in a company of 10's of thousands of employees.