What's missing from the initial comparison is the fact that smartphones opened up all sorts of conveniences, which is partly what makes them so addictive. Rock music, D&D, etc, these other things that were crusaded against offered no convenience for all, so a conservative mind saw no value in it and attacked it as something that warps or rots young brains. Smartphones obviously do that and worse, but because they offer all sorts of helpful tools in our daily lives, we let it slide.
When I was in high school in the 90's, the famed Texas Instruments calculators were often banned in some maths classes because, as was said at the time, we were "not going to be walking around with a computer in our pockets all the time," so we needed to learn to do the work. By the time my younger brother passed through the same classes, they were required to have a graphing calculator because it actually helped kids complete the work. And play Dope Wars.
While we do tend to overreact to new tech, ways of thinking, games, music, etc, there's something inherently oily and snakelike about a thing that brings convenience to our lives the way smartphones or cell phones did. They slip in, comfortably at times, settling into our habits and routines while simultaneously altering them. We end up manipulated by it and before we know it, we can't set it down. In the case of smartphones, our data became the commodity, a mere decade or two after we were worried about tracking devices in cars or phone lines being tapped. But the smartphones kept delivering on their promises, which kept us hooked.
As someone who recovering from alcoholism, I struggle to call our love of smartphones an addiction, but if it helps people be aware of the dangers, by all means, use the term. To me, the problem of smartphones is manipulation at the deepest cognitive levels. We started offloading some thinking to them and who could blame us? We had the store of human knowledge in our pockets! We could play a game instead of sitting idle on the train, gamble with online casinos to try and win some extra cash that week, keep up with the Joneses on Facebook or get into a heated debate on Twitter during our lunch break, check banking, stocks and eBay sales, etc. We no longer had to carry a separate device to photograph or record the moment. The list goes on and on. But in the end, it altered our behavior just enough that we allow ourselves to be controlled by it, monitored by it, and bought and sold by it.