4.1 To know how to persuade them. If the suppliers interested in your product, there must me something that similar with their company.
4.2 For example, A company selling an engineering machine and wants to sell a products to b company, which is a sugar company and need to use an engineering machine from A company. So, A company will know how to persuade the suppliers to buy their product by presenting a property of products to them and have some discount for B company.