Debug builds have extra code called assertions to inform us when assumptions or surrounding code are incorrect. For example, assertions can reliably tell us when third-party code makes common threading mistakes, even though the crashes from those mistakes appear random. I find about a third of my bugs by noticing assertion failures, and it usually isn't the assertion that's incorrect.
In several bug reports from users who were hitting frequent crashes at random, I suggested that the users compile their own debug builds, hoping that assertion failure messages would lead us to the cause of the crash. Few of the users succeeded, since the compilation tools and instructions were written with programmers in mind. Now that pre-made debug builds are available, we may be able to make more progress on these kinds of crash bug reports.
Big thanks to the release engineering team for making these builds available!