>> Yiddish is Yidden�s common tongue.
How non-inclusive of you! R Yaakov Kamenetsky while visiting r Auerbach’s yeshiva suggested that Maschiach will come out of it, because the yeshiva had top shiurim in Hebrew rather than Yiddish, enabling Sephardim to join.
So, it is about context. In some circumstances, Yiddish helps preserve Jews, in others – divides.