The reason I don't think so has precisely to do with probability -- despite the fact that we don't know all about genome evolution.
Nothing else? Really?
Improbability or implausibility of a hypothesis is not enough to support an alternative model; it is simply enough to cast the hypothesis into doubt and intensify efforts to look for other explanations.
That depends on WHO is making that determination and what they're using as evidence to reach that verdict. I mean, ALL hypothesis have a level of doubt surrounding them. That's why they're
just a hypothesis. But just saying "it's improbable" doesn't suffice, because, with every hypothesis, not all the details are known.
It's perfectly relevant to gauge the robustness of a particular hypothesis for the origin of a given system.
Hypothesis by definition aren't complete theories, so improbability isn't relevant. We don't have all the details yet, like in my example of Newton, so it may seem improbable for now but not once we have all the details.
Remember the calcium atom ending up in CS's arm? How improbable would that seem had solar fusion being a vaguely understood hypothesis? Highly improbable! But, as you detailed, not so much once we figured it all out.
- Oni