I agree that the technology is not perfect and everything you want it to be but for 99% of the population who get no walking at all, it is a wake up call and helps a ton. I lost 20lbs in 6 months because of wearing fitbit and jawbone.
...And no, the bathroom scale is completely non-networked, my smartphone simply prompts me to tap in the reading every morning.
If your goal is to "lose weight", then forget activity-trackers, because your main tactic should be controlling the input side. It's far easier to not eat 200 calories than it is to burn those 200 calories off later at the gym. It's also cheaper than buying expensive techno-nostrums / shiny-toys.
It's a small motivational tool, that's all. Nobody needs it, but it's nice. I've lost 28 pounds fairly quickly, thanks to a combination of walking and calorie counting with MyFitnessPal (Fitbit's food database is inferior).
I do think they really need to improve durability. My wife is on her third fitbit flex in 6 months.