I wonder if your experience is typical. I have a lot of projects on github (and have for some time), and I’ve gotten something along the lines of four issues/pull requests total. Having entitled trolls bothering you about your code doesn’t seem like it’s something common on github (although clearly they could be giving you the tools necessary to handle this better), and is (paradoxically) an indication that your project is extremely popular.
Part of the point of a system like github that makes forking projects easy is to eliminate pressure on upstream developers to implement features. In other words, while on an older project management system like sourceforge and google code having requests for features directed to the original authors of some code would be normal, github goes out of its way to shift the pattern such that people who want features are expected to create a fork and implement them themselves, before optionally issuing a pull request to submit the patch back to the source.
I wouldn’t blame github for this. Instead, somehow, you were targeted by a group of assholes who are too incompetent to implement the features they desire and too lacking in empathy to realize that you have more important things to do than to follow their whims. It’s absolutely appropriate to expect them to do their own homework, so to speak, and it’s a shame that they don’t seem inclined to do so (or to observe the basics of decorum).