The reason is that, based on facts, only facts are right, so astrology and geomancy are based on facts. The contradiction between them is only the theoretical agreement, because they serve the facts, so what is wrong is wrong, not the problem between them. All applied sciences should be compared with facts, not between them. That is not an understanding of reality and harmony, but a stream of sophistry.
So your question is, is this credible? The facts are accurate and credible.
Moreover, from the perspective of development, there must be idealism in the development of any theory, and the conclusions drawn by various wrong methods are incorrect, but if they can be circulated for thousands of years, at least most of them are correct.
So most of them are credible, and only a small part is wrong.