Why don’t Orthodox men wear neckties?

I (a non-Jew) spent a fair amount of time this past week at Mount Sinai Hospital in New York, where a friend was being treated for a heart condition. Mount Sinai is the preferred hospital for many Orthodox and Hasidic Jews in New York. I noticed that Hasidic (and some apparently non-Hasidic Orthodox) men would wear dark suits or frock coats with white dress shirts, but never a necktie. Is there a reason for this?