The truth is that there is no IT "profession." Most of what IT managers know about IT they learn from vendors, consultants, and folks like Gartner. Because they feel isolated, and because the IT vendor/consultant/media system encourages them to worry about such things, IT managers tend to feel they must have their important decisions validated and Gartner is the most popular place to find validation. [...]
Much of this comes down to the decided lack of professionalism in IT, which is after all a very new job classification. There is a huge difference, for example, between someone with an engineering degree and someone in IT who calls himself an engineer. Real engineers are often valued employees. Their opinions matter and they have real responsibilities. Good companies know engineers are important to their business and treat them accordingly. But IT workers are a commodity and are treated as such. Many IT workers are clueless about the technologies they are working with. They aspire to be project managers and are often not very good at that either.
Into this knowledge vacuum come the vendors, who want to sell stuff, and the consultants like Gartner, Forrester, IDC, and the Yankee Group, who need IT managers to feel uncertain about every decision except the decision to buy something, anything. Then look at the number of "research reports" that are commissioned by vendors. Uh-oh.