Part of the problem with accepting gifts from vendors is that it can hamper your objectivity when either making purchasing decisions for your company or recommending products or services to clients. It's important to be as objective about the decision as possible. Particularly if you are an employee of a company, you have an obligation to consider the company's interests first and buy products and services without being biased or considering your own interests. Larger companies have strict human resource policies about what is considered a gift and what dollar value of gift needs to be reported to the company. There are certain industries, such as health care, where the giving (and receiving) of gifts raises serious implications such as the propriety of medical treatments given to patients and where gift-giving starts to look a little too much like bribery.
Creating a MAP will take no more than an hour of your time every month and will keep the lines of communication open, ensuring relationships with investors remain strong, and ultimately helping early-stage startups succeed.