Many religions that have shaped civilizations were heavily based on divining information about human affairs and terrestrial events by studying the movements and relative positions of celestial objects (i.e., astrology). Multiple Rome emperors had court astrologers, for example.
Yes, but not of the major religions are about that -- Christianity, Bhudaism, Jewism, Islam, etc.
Nor where the religions like the ancient Greek, Egyptian etc that did contain such rituals, predominantly about those.
So we can quite easily consider astrology as something either separate or a very small subset of any religion that shaped civilization...
The simile being that the various reglious Gods are also not real?
That's irrelevant, because religion, as a human practice, and the actions, practices, decisions taken based on them are actually existing and actually modifying the world. So that would be more like a placebo that made you do X (e.g. go on a diet) and you see effects from that. In that case, it's not a placebo anymore.
Well, religion has been studied for evolutionary advantages.
And of course religion has shaped and sustained whole civilizations, arts, philosophy, etc, in ways which astrology did not, and in many ways that people still identify as beneficial.