Experimentalists often tend to get more credit than theoreticians. People (apparently along with the Nobel committee) prefer results over potential theories.
That appears to be so, but the committee's application of that preference is rather self-contradictory. Without an explanation, the result would not even have been a contender for the prize, and it was Alpher who first provided the explanation.
As Alpher also showed that the universal ratio of hydrogen and helium isotopes can be explained by nucleosynthesis in the big bang, he seems to have been seriously overlooked.
Yes. As the article states, theoreticians have already suggested 60 potential dark matter explanations. Teasing those apart requires careful experimental and theoretical work, and that's what the Nobel committee is (supposed to be) looking for.
