That would again suggest that it's marketing (that is, the process of finding distributors and buyers) rather than production and design that are the principle cost-drivers. A seller of "dumb" devices has far fewer potential buyers (or at least perceives as such), and fewer channels for distribution, so they're going to have to focus more effort, and cost, on sales and marketing. It's not the cost of designing or producing the products, but of matching them to distributors and buyers, which would dominate.

I'm not certain of this, but I'm fairly confident it's a factor.