When the Jews immigrated to the United States it marked a huge cultural change in their lives. Suddenly, they were transported from the shtetls, (small village or town), or from the ghettos of small Eastern European cities, to huge urban centers of the West. Here instead of working in small shops, they went to work in the infamous sweatshops. Suddenly they were in the thick of the industrial revolution. They had left behind their familiar talmudic way of life. They were dressing differently. They were using machines. They were used as machines.
The Jewish immigrants were in a rush to be modern, to leave behind the strict observance of Jewish law that kept them separate from other peoples. They wanted to be a part of the wider world. They struggled to break free from the authority of the Rabbis. Their Rabbis concentrated on scholarship of a narrow kind. The world of the Rabbis centered on study of sentences, of words, written long before. According to the Rabbis the words of man could not compare to the Word of God. Manual labor was looked down on. The world of the Rabbis was isolated from the world of other people and the Rabbis wanted it to stay separate.
The Yiddishists were secular Jews. They believed that the Jewish people needed to be a part of civilization not apart from it. Many Yiddishists were learned Jews. Some had been Yeshiva (Rabbinic Academies) students and some were sons of Rabbis. They loved their culture and history. They did not want to assimilate and disappear. They just did not choose to live in a separate world.
In my youth there was a vibrant Yiddish press that helped the immigrants become modern, become American. It helped the new immigrant cope with this new life. In the twenties and thirties the Yiddish newspapers and periodicals had a golden age. They advised the immigrant. They showed them how to write a letter to their boss or to their children's teacher. They drafted a form (model) letter in English with a Yiddish translation. The immigrant only had to copy the English script. I still have some Yiddish recipes my mother cut out of Der Tug. When you paid for a yearly subscription, the paper gave you a premium. That is where my parents got their first metal menorah and where my mother got her hand crank grinder. She used it to make gefilte fish.