I do not think "amateurs" is a good description about the people writing the code - most will be highly technical people with lots of experience. And "loosely coordinated" can be applied to many "corporations" as well.

I think it matters that people coding in open source do it because they care (similar to your idea but on the positive side). If you want to make something nice/working/smart you have more chances to succeed if you care than if you are just being paid to do it (or afraid that you will be embarrassed)