Exactly.
If you follow the parent create method into the commit method, you will see $this->rules()->$action(...$argumentValues); Which then calls the corresponding rules, in the case the PageRules::create method.
You should be able to follow these methods by CMD-clicking on them… Or you use a step debugger and set breakpoints: First steps to start debugging with Xdebug | Kirby CMS
I already convinced someone else 
Fileupload over routes - #16 by Microman