Who needs teachers?

Nowadays with the great availability of the interenet,
And also access to knowledge either through the printed or electronic media, it seems the roles of teachers are diminishing. As we can see fromt he previous post I can get knowledge from a professor in the UK without ever even needing to go overseas and spending the money. Having read his article and memeorised it one can say one is as informed as him on that particular matter.
However without teachers how are we to know what is crap and what is not. Teachers are still needed to guide us. Teachers are needed so we can avoid rediscovery. Put simply they are compasses. Textbook are charts. these by themselves do not make a voyage which we must undertake and be responsible for ourselves.