Take this into consideration:
I post one of my software projects that I had written for school, and give it an open source license, and place it online for people to evaluate and contribute their thoughts. I do this in hopes that other more experienced developers will be able to optimize or add new features to my already existing program.
But how would I prevent malicious people from tampering with that code? If my project is the victim of multiple, continuous attacks and vandalism, it wouldn't be efficient on my part to "rollback" to earlier revisions. Not only would this be an annoyance, but it could make the project look less attractive to prospective contributors.
Can I restrict or "approve" contributors to help me improve the project? I'm nervous that doing so would violate the Open Source concept. As seen on the Open Source page:
Can I stop "evil people" from using my program?
No. The Open Source Definition specifies that Open Source licenses may not discriminate against persons or groups. Giving everyone freedom means giving evil people freedom, too. Fortunately, there are other laws that constrain the behavior of evil people.
Does this apply only to the audiences of my program, or would it apply to people who try to contribute to it as well?