This may be kooky, but isn't it a requirement in science to have independent researchers confirm your results?

According to this textbook:

To qualify as scientific evidence, observations must be quantitative and repeatable.

The way it works, is that one makes an experiment, then publishes it in a reputable science magazine. Other scientists see what was done, and then redo the experiment by themselves to confirm or refute your results. This is the method by which science works in practice, to my knowledge.

Now, if we look at the moon landings from this perspective, they are a fail. There was only one experimenter: NASA. There was no independent confirmation that it can be done. They didn't even try.

Yes, there is evidence, moon rocks and image and video footage and whatever, but that's not the point. The point is that this greatest feat of humanity has never been confirmed by others to be possible. Thus, it is unscientific to regard it as anything more than a theory.

What do you think?