Legally, that phrase doesn't mean squat anywhere in the world. A copyright notice is not a license. Stating that you own the copyright to a work is not a license. It also has no bearing in the sense that you can say "all rights reserved" and still unwittingly give people implied license to use the work for, say, reading it by sharing it publicly.

> I never said it did.

You said that it would be easier to defend it in court if it was licensed. I argue on the other hand that it should be easier to defend in court if it's a clear cut copyright infringement rather than a matter of interpretation of some license, whether the license is at all enforceable and whether it's a copyright case at all and not a matter of contract law. Granting people an explicit license to your work adds a lot of moving parts.

> My point is, you are not helping anyone by not explicitly licensing things. You might know what rights exist if no license is specified, but not everyone does. I've seen terrible advisers and lawyers say 'well, there is no license and the source is there, so it is "open source" and fair game'. having an explicit license of rights would help to discourage all but the really dense folks from abusing it.

I think that someone who is dense (or more likely, unscrupulous) enough to use someone's work without a license to do so is "dense" enough to ignore the terms of a complicated license. We actually see that all the time, for example GPL licensed software being used in ways that don't comply with their license. The "open door" really happened already at sharing the code publicly at all. There will always be people that just don't give a shit.