Vettel had the whole pack around him, did Hamilton?
What's that got to do with it? Hamilton had two cars around him, one in front (a back marker) and one slighty behind on his inside. He positioned his car in the only possible way he could to avoid incident. Hulkenburg lost the back end of his car and as a result took out Hamilton.
Vettel had a car to his left, on the inside of the corner, and turned into them, ending their race. He didn't have anyone in front of him.