The internet provides a communications platform where teaching is a possible activity.
Note bolded above. I did not ascribe teaching to the internet. The phrase used was "the internet and what we can make of it."
Now why exactly do we need schools?
Trite answer - to give teachers jobs...
Not quite so trite answer - to teach the basic skills necessary to enable the student to learn (e.g. reading, source evaluation, etc) to enable self led learning (from the internet or elsewhere) - although you could argue this /could/ be done in the home, although not everyone has the time, inclination, ability to do so...
One other part answer, not all students can simply learn by reading about something - the internet, good as it is, doesn't accommodate kinaesthetic learners, for example.