Writers have been known to be very reclusive beings, they withdraw to immerse themselves in their work. They shut out everyone to hear their characters more clearly. While seclusion can serve a purpose it is best not to go to extremes when you lock yourself away to write. Remember you are creating characters that must be real and vital and have likes and dislikes. Being around people help you to create more colorful characters.
There is another reason writers need good friends…A friend won’t be afraid to tell you when you need to rewrite a scene or you have some inconsistency with another part of the story. A friend won’t sugarcoat your mistakes they will care enough about you to point out where you need to put a comma!