There are hobbyists who might want to, I don't dispute that, but what I'm saying is there aren't enough. You need a pretty big critical mass before the economics start to make sense and something like what happened with 3D printers becomes possible. Projects at the scale you're talking about take a massive investment of time and skill independent of how long it takes to assemble boards, putting them out of reach of the vast majority of people simply because they don't have the time. Not to mention the cost of such a project; if you can afford to invest a thousand or more dollars in a hobby project then you can probably afford the tools you need to do it, too. Maybe I'm underestimating and there are tens of thousands of people out there wanting to build complex data logging networks with hundreds of nodes just for fun or some other equally ambitious project, but I doubt it.

> I think your analogy falls down because an automatic bottlecapper does the same thing as you'd normally do by hand.

That was my point. A pick and place does the same thing you'd normally do by hand with a pair of tweezers in about 10 minutes for a board of moderate complexity. Doing surface mount work by hand with tweezers is pretty easy. The only thing a pick and place enables is for you to do things at a large scale, because they have a substantial overhead to use that you only start to recoup around 50-100 units or more. Now, if we had some revolutionary device that you could set up in 10 minutes to feed dozens of parts and cost $500 then hell yes, I'd want one too. But I don't think that's possible at present no matter any economies of scale or design optimization, because a pick and place is actually quite a complex machine by simple necessity.

Not to mention that placing parts is only part of it - you still have to fabricate and drill the boards, load the machine, clean up any mis-places, reflow them in an oven, manually place any through hole or awkwardly shaped components and solder them, cut the boards, test them, program them, mount them, etc. A pick and place would definitely save you some time if you really want to do such a large project, but by itself I don't think it's gonna be enough to really make it accessible to an individual in their free time. I'm not disputing that they would be beneficial, just that they make sense for an individual working in their free time. Especially when you consider that contract manufacturing isn't that expensive, though it does come with its own set of hassles.