they should [...] be [...] trying to determine whether their products do indeed have bugs without placing a lot of that burden on customers to create these example projects and reports.
Depending on the size of the user base, this is usually unrealistic, unfortunately, even for very large companies.
When a bug is suspected, it is part of the job of the user to demonstrate what the bug is, and therefore narrow things down in order to demonstrate the problem for someone more technical to investigate the issue efficiently. Support teams or communities can help guide the investigation, but in the end a proper bug report that actually demonstrates the bug in the simplest possible scenario has to be submitted.
That's what QA teams do internally in game studios, they try to understand as much as possible about a possible bug (esp. how to trigger it) before demonstrating the problem to the most relevant programmer. And that's exactly how it happens when dealing with big companies as well, like Microsoft, Sony, Nvidia, Apple, etc. When you find what you suspect might be a bug in the latest xbox sdk or a recent nvidia driver update, which does happen on a very regular basis btw, you don't send your whole project asking for someone to investigate. You recreate a simpler project to isolate the bug and send a test case for review.
The user knows its projects, he's the only one to know what to remove and what to keep to reproduce the bug ; if he doesn't, the user doesn't know enough about its own project. When it takes a few hours or days for the user to recreate the bug in a simpler project, it would take weeks or months for any external developer or support team to start to understand what a decent size project is all about. If the suspected bug is about sprite animation, you don't want the support team to thrall through dozens of thousands of events or lines of code that have nothing to do with sprite animation (controls, audio, effects, levels, physics, etc.). If, for example, a sprite doesn't animate as expected when some specific physics properties are applied to it, that's what the bug report should be about, not "something doesn't work in my project" (just exaggerating but I'm sure Ashley must receive quite a lot of similar complains)
The main "problem" with C2 is that it's almost too easy and/or flexible to use, therefore it is possible for people with very limited technical knowledge to create quite complex things. Which is great - nevertheless, it also means that a very large majority of the "suspected bugs" are just misuses of the product