Dear Always,
Jews do not assimilate or convert because of close contact with the outside world. Look at the Jewish communities in the Arab lands. Almost no assimilation until World War One. The reason why Jews leave the fold is because they feel like there is nothing there for them. Spiritual and physical. Shutting out the world offers less creativity, which leads to less options, which speeds up the process. When we really look, the rate of attrition is the same throughout all orthodox groups. The salve for assimilation is Jewish Education.