I'm making two assumptions here: firstly that there is a hierarchy of contributors, where triage doesn't have to be handled by the guys right at the top; and secondly that the first few submissions by a new person aren't major--they are going to attempt something small first. If the latter isn't the case, the response should be "sorry, we appreciate your help, but try to get some minor bug fixes in before a major architectural change".
That's actually not the way the real world works though. The primary "jerk" projects (mostly the kernel and Linux infrastructure) are dominated by submissions from paid, professional developers working on support for new features for their employers. These people are routinely coming from closed-source backgrounds, don't understand the project, don't write new feature with an eye to maintainability, and have an affirmative requirement from their managers to get their submissions accepted. As I mention, sadly, I'm in this set more often than not.
That's just not a recipe for fun. The "hair trigger rejection" filters are there because of all the junk that gets thrown at the maintainers. And either it makes them grumpy or is acceptable only to people who don't mind being rude. Either way, the "jerk" bit is a direct correlation.
