French is interesting because it evolved this so-called "dummy subject" pattern (which is actually called "subject-prominence") for an entirely different reason than English.

French is descended from Latin, which is "pro-drop" in the sense that you'd drop the "dummy subject" and simply write "pluit." Later, Old French, like English, lost most of its cases. Because of that, many word endings started sounding very similar (a problem known as "agreement syncretization"). The pro-drop "null" subject disappears in the record roughly as that happens, presumably to help disambiguate.

This is an entirely different path than English took, and it's also not a path any other Romance language took. Spanish isn't even subject-prominent. It fully allows the "null" construction, e.g., "llueve", which literally is just "rains."