I think it's fair to say that few vendors spend time actively thinking about ways to lie about what their products do. Rather, there's a fundamental tension between your needs and theirs: Vendors need to grow their companies and you need to run IT operations as efficiently as possible. This tension often leads to products that either don't do what the vendor claims, or that do things you really don't need or want.
I recall reading that if Cisco Systems grew during the second seven years of its life at the same rate it expanded during the first seven, every person on the planet would be working for Cisco. Although not even Cisco would set itself a strategy like that, it does point out the tremendous pressure that Cisco's management has felt to grow. When tech companies are young, they can achieve incredible growth simply by delivering exactly what the customer wants. But eventually, everyone who wants one has a good 10/100 switch at the network edge, some powerful core switches, and routers out to the Internet. These products don't wear out, so Cisco and its ilk need to find ways to convince us to upgrade.
Once raw performance is no longer the driver, maintaining an upgrade cycle gets dicey. We've all realized that gigabit-to-the-desktop is a silly waste. So what, wonder the networking vendors, could the network do for customers that it doesn't do already? If it could provide phone service, then all the edge switches will need to be upgraded. Once the network is doing that (or supporting some other new capability), we're sold NAC, and again all the edge switches need an upgrade to support it. The strategy for rolling out these technologies is built more around the vendor's need to grow than its need to satisfy customers. But don't blame Cisco. It's happened with all mature tech companies, and will happen again with the newest generation too. Google will find it hard not to be "evil" when its markets are mature and double-digit growth becomes elusive.
Art Wittmann is editor in chief of Network Computing. Write to him at email@example.com.