As others have said, it really depends on the student. With the large class sizes they used to have around here, much of a student's time was spent on their own anyway. A teacher can only go as fast as the slowest student.
What can be negatively affected is socialization. Without access to other kids, they won't learn how to buy drugs, how to fold when stuffed into a garbage can, or how to be bullied. Without being with other students, students will be forced to make "internet friends (and they aren't always what/who they claim to be).