My hunch is that the commonalities stem from intermingling of esotericism, in that the people interested in one of the above is likely to be interested in at least one of the other one's and so it's there's no coincidence whatsoever that common threads run throughout these diverse topics and practices.

Another explanation that involves no need for coincidences is that there was a guiding hand pointing all of them towards existing ancient knowledge that could serve each of these in different ways.

My third postulate is that humans burdened by curiousity, open to new ideas, well developed critical thinking faculties, well educated and adverse in nature to tyrannies, unearned authority, individuality, as well as social community tend to gravitate towards ideas such as these. That where they overlap, is not deliberate, nor coincidence, it's just that those who seek the truth apply this ideology to everything in their lives and the commonalities were all developed independently of one another and I'm only noticing them as a sortbof cognitive bias.