For those who like a lot of interaction with a variety of people, tutorial learning/homeschooling will feel like it's lacking. Of course, many homeschoolers make up for that by being part of co-ops, attending school part-time or finding, or creating, other group learning activities. Homeschooling doesn't mean in and of itself that you don't do things with other people.
I suppose if you never took part in any kind of group class and went off to college, you'd find it to be a hard adjustment.
Other than that, I'm not sure what true disdvantage you can find. Tutorial learning and homeschooling are the traditional way of learning. It was THE way that the educated upper classes in Europe were raised: the mother either taught them or a tutor or governess was hired to do it. Their education was considered superior to all the lower classes. It's a time-proven approach to education.
The biggest disadvantage of homeschooling is having to listen to naysayers who don't know anything about homeschooling and spout all kinds of false things.