A smartphone is a tool like any other, and it can (and often is) abused in ways that negatively affect the user, but they don't have to be. I finally got one last year, as it enables me to have many functions in one relatively small and light device when backpacking—it's a communication device, navigation device, reading device, and camera. I don't use Facebook, Twitter or other social media services (at all), so my phone doesn't eat away at my life. But it can be a valid choice to avoid smartphones as well, and I respect your decision to do so.
You could also consider a dedicated Kindle device—if it on its own was lighter than the guidebook, you'd already be winning, plus you could take other reading material with you as well for no additional weight gain.