Like I said, it’s not about the export formats, if they want to access your original files they would have to install Blender to be able to open them. There’s a lot of reasons they would want the original files rather than the files you export to the game.
FBX is pretty a pretty standard export format for games and the issue is just that Blender doesn’t have a good FBX exporter, if they wanted to they could improve that.