Good for you. Sounds like you don't need this program. Since you're aware that there are people who treat "Downloads" and "Desktop" like a flat filesystem, presumably you can understand why this would be useful to them and others.
Maid (and Hazel) certainly aren't for everyone. The original intent behind making Maid was to automate part of what drivebyacct2 describes. I just got tired of manually doing things that could be easily automated. :)
Maid isn't only for cleaning up Downloads, etc. -- it may even be helpful for drivebyacct2 to organize things in other ways. For example, this is a Maid script I've reused many times when handling SRT files for videos:
I'm guessing the people that would really benefit from it have never heard of GitHub and think that Ruby is a precious gem. I don't mean to knock the work.
If you are guessing that all engineers who understand how to use the command line are well-organized, I can provide you at least one certified example of one who doesn't match your worldview. This is awesome.
I can certainly see where you're coming from. Many of those people would probably benefit from Hazel more than Maid, however. :) As it stands, Maid is somewhere in between hand-crafted shell scripts and a user-friendly GUI (but definitely closer to the former).
That said, Maid has certainly helped me out, and I'm happy that so many others have found it intriguing. (Thanks for the comments!)