Hud what mazca is probably referring to is the secular Yiddish world that most people don’t know too much about because the movement never got to strong in the states. In mexico for example you have Jewish irreligious schools that teach Yiddish and no Torah. You have Yiddish sport centers that put on plays without tziniut in Yiddish. There is a conservative shul that uses Yiddish.
So what we are really saying is that there is alot of Yiddish apikoresut but many people in the states have never seen it because somehow that movement never picked up there.
And another point these people think that by knowing Yiddish it exempts them from doing mitzvot because they know Yiddish!
It really is very sad.