[pawadu]

What are the benefits of accepting kicad files instead of gerbers?

I understand people can make errors when generating gerbers but they can also make tons of errors when sending you the kicad files (like not including custom libraries).

[paddi91]

KiCad Pcbnew files contain all required footprints etc., unlike the schematic files you need no libraries or such.

Creating Gerber files is sometimes hard as different fabs require different Gerber files. Starting with the file extension ending with floating point precision.

One argument against uploading KiCad files is copyright as the fab could reverse engineer the PCB. But this does not count for open source projects and is really unlikely to happen.