Anyone who regularly learns Rashba, Ritva, Rambam, or Rabbeinu Chananel sees that these Rishonim were clear masters of the Yerushalmi as well as the Bavli. Such does not seem to be the case for Rashi and his disciples, who make almost no use of the Yerushalmi. Indeed, a common methodological insight of the mainstream Ashkenazic commentators is that they make almost no use of the Yerushalmi (except, perhaps, Ra’aviyah). Mordechai, Yereim, Semak, et al. nearly never cite the Yerushalmi.
Rabbi Michael J. Broyde, “May the Jewish Daughter of a Gentile Man Marry a Kohen?”, The Journal of Halacha and Contemporary Society 47 (Spring 2009), 100, n. 6.