It really does depend on your situation. At a prior employer, about three years ago, we brought on an intern as a developer who wanted to skip college. He felt he wouldn't learn anything in school and that he should go straight into working.
He was smart, but after awhile it was decided to let him go for a couple of reasons - mainly around professional behavior and maturity. He couldn't focus and management didn't plan for/have the bandwidth to really properly handle an intern in this situation. Some of us tried to help where we could, but already having to work 60+ hour weeks left little energy/time to do so.
In the years since he was let go, he has matured and is turning out some great projects and working at a company that is really happy to have him. It took time and a good amount of job hopping for him to get his sea legs.
College is just as much about learning as it is about maturing and getting out on your own. Depending on the person, some people need this and some may not.
In general though, I'd say a lot of natural maturation occurs between the ages of 18 and 22, or even older for your masters degrees and the like.
Anecdotally, I once worked with a girl who on paper was sharp as a whip -- 2 masters degrees from prestigious colleges, top of her class, etc., but in person, was quite socially awkward and had absolutely zero real world experience, as she had only ever been a professional student. She was responsible and mature enough to do the job, and she definitely had plenty of book-type scenarios upon which to apply her vast education, but in the little things, that typically aren't taught out of books, she floundered. Now I think she holds a great title in finance at a decent bank, which probably suits her education better, and hopefully affords her less social interaction than when I knew her.
Another thing that bothers me about college (I didn't attend, though I constantly consider enrolling now) -- is that it means that degree seekers end up in the job market so late in life. I had a portfolio of applications I'd written, technical expertise, and a good working reputation by the time most college grads are just entering the job market.
Obviously, I'm potentially discriminated against by companies who heavily value college degrees, but at least for early job markets, it seems that (outside of silicon valley anyway) the college grads who had to compete with others like myself were at a disadvantage.
He was smart, but after awhile it was decided to let him go for a couple of reasons - mainly around professional behavior and maturity. He couldn't focus and management didn't plan for/have the bandwidth to really properly handle an intern in this situation. Some of us tried to help where we could, but already having to work 60+ hour weeks left little energy/time to do so.
In the years since he was let go, he has matured and is turning out some great projects and working at a company that is really happy to have him. It took time and a good amount of job hopping for him to get his sea legs.
College is just as much about learning as it is about maturing and getting out on your own. Depending on the person, some people need this and some may not.