I don't understand the purpose of these extreme licenses. If you don't want to restrict the usage of your software in any way, why not place it in the public domain?

As I understand it, the point of owning something is to restrict what others can do with it. Some people want that. For example, some people choose to own the software they write so they can license it under the GPL. They want restrict my freedom to limit what others can do with any modifications I might make. If that's what they want, then retaining ownership makes sense.

If you _really_ don't want to restrict others in any way, why maintain ownership? Why take on the risk of liability, or go to the bother of disclaiming it? It's software, so giving it to the public won't deprive you of its use.

But then, I am not a lawyer. Am I wrong? Are there downsides?