I think Co-star is fascinating for this reason because it's not so much the science of belief but the charisma of truth. People like it mostly because it's kind of sassy. For the most part, sun-moon-rising offers a quick and dirty way to assess relationship compatibility in a dating-app world where rejecting everyone and accepting everyone is tedious and exhausting. It's also a particular love language of understanding and explaining what it is you look for and being aware of how people explain themselves, for those that use it.

Technically, astrology is based on algorithms observing data of the planets positions. For the most part, to the naked eye, and to human sensibility, the planets seem to behave in harmony, resonance and stability. In reality, the long-term behavior varies chaotically. It's an n-body problem, which is as of this time of writing, unsolved. Generally, that doesn't mean it hasn't been answered, rather it means that solutions satisfying specific conditions cannot be determined by the criteria of uniqueness or existence.

But yeah, if you're going to make short term observations of a chaotic system, a sporadically random system is basically just numerical approximation. You don't need to rationalize irrationality, because you can't.