If I explain a phenomenon using 10 postulates (of some fixed length) and you explain it using 10,000,000,000, your theory gets demoted (even if we don't know anything else about the two theories) because it has more ways to go wrong. If you accept that this is true in a big way in the extreme case, you should accept that it is true in a small way in more mild cases (e.g., 10 postulates vs. 20, or 10 postulates vs. 100).