It was generally the gemara which was brought to other countries first, which meant it was learned first, became prominent before Yerushalmi was brought over, and therefore became preferred.
As in, for example, at least some tosafos had Yerushalmi, but by and large preferred referencing Bavli because many didn’t have access to Yerushalmi and it seemed more “respectable” in a way to reference Bavli which was more “mainstream.”