I suspect the professionalism aspect is a salient point - given the accessibility the platform offers, whilst many of githubs users are professional developers doing their day job, they might equally be somebody trying to build a webpage for their cat, who stumbled across the repo looking for a troubleshooting guide.
With platforms like github, it's difficult to attribute the degree of merit any given comment deserves, so we kinda have to take them all at face value. That can be pretty brutal at times.
