Slightly tangential but I've found it insightful: there are studies, e.g. [0], showing correlations between lifespan and date of birth. Causal factors could include for example seasonal viral infections, lesser amount of vitamin D in the winter, etc.
Of course, this tells nothing about well-witching, but illustrates that at least some old beliefs aren't as unreasonable as one might think.
Even without evaluating the quality of the study, I don't have a hard time accepting the notion that the season of your birth may affect your average lifespan by a few months. It is a very modest claim.
The claims of astrologers are not at all like this. They are vastly more specific.
Okay granted; my intent wasn't to justify astrology either, but merely to encourage prudence when dismissing "old ideas." To be clear, I'm not talking about modern astrology, but really about old beliefs that could have been built on repeated observations, but weirdly/poorly phrased.
In The Republic of Plato, there's this idea of rotation between political regimes[0], and it's explained by the way each generation treats the next one. Down to Earth example: think of overprotecting parents making their child unprepared for an ordinary adult life.
Now of course, this is again distant from the discourse of our favorite astrologers, but if you squint a little, there are conceptual similarities.
Thinking about it a little more, and on point to your original remark, I wonder if the fact that a considerable amount of people like to believe in astrology isn't tied to the same instinct that made old people personify everything and anything as Gods: a strong tendency to see order and intelligence in chaos.
After all, science is still about doing just this, minus the anthropomorphism. So, not so shocking: just human nature at works.
While I don't think this particular wikipedia page is especially concise, I do think it's a great jumping off point for links you will find interesting:
I first learned about the link between temporal lobe epilepsy and hyperreligiosity from Robert Sapolsky's Biology and Human Behavior. From your comments I think you'd find it as interesting as I did.
A Facebook friend was talking about how overwhelming and chaotic her life has been feeling lately and people were chiming in to say they were in the same boat and attributing it to the Mercury retro-whatever.
Must just be a coincidence that it's back-to-school season and everyone is transitioning out of their summer routines into school-mode.
Of course, this tells nothing about well-witching, but illustrates that at least some old beliefs aren't as unreasonable as one might think.
[0]: https://www.pnas.org/doi/full/10.1073/pnas.041431898