Because it is easy to say and typical for English. In English "y" at the ends up as "ies" for plural. Whatever the rules, eventually whatever is easier for loc

Because it is easy to say and typical for English. In English "y" at the ends up as "ies" for plural. Whatever the rules, eventually whatever is easier for locals to say will be what people go with. > The only other Slavic-to-English example of this sort I know is pierogis, from Polish (the nominative singular form is pieróg). Not speaking Polish whenever I heard "pierogis" in English, I assumed all Americans meant was Russian "pirogi". So was expecting fluffy yeast leavened baked goodies, instead I got boiled vareniky/pelimini/dumplings.