The engineers wouldn't have made world changing products without his guidance. There are many books about this, even by the employees themselves such as Creative Selection and Insanely Simple, which talk about how Jobs' product vision simplified much of the UI and UX and therefore product for regular users when engineers instead wanted to add more features and complexify the product. Steve was not just a salesman handed a product and asked to sell it.

Steve Jobs said no. No to 'stupid' ideas and no to 'cannot be done'. That leads to some products being bad (eg mac cube) and other to be interesting to build on (iphone with no app SDK).