For 3D printing this is becoming less true every day. 3D Printers are now extremely cheap, where sub-$300 printers make sense at low scale usage. A typical print from an outsourced printer like Shapeways might cost you about $20, and once you factor in the cost of the material when you print yourself, it only takes about 20 prints for the printer to pay for itself, and you have the added benefit of having your print in an hour rather than a week.
Also, it's just lots of fun to work with the printer.
3d printed parts and PCBs can be done in as little as 12 hours. You can then without any modification do small production runs anywhere from ten to a thousand pieces (which isn't unrealistic outside consumer hardware). You could even 3d print moulds and do injection moulding.
I think partly why people say that hardware isn't iterative enough is that they are doing it the wrong way. They spend too much time on prototyping, which means they then have to make everything perfect for a large production runs to average out the costs.
Yes, you can do design prototype revision A, B and C, then do production prototype A, B and C, and finally production version A, B and C. But then you have spent a significant amount of time and money refining prototypes and adding features. That forces you to large production runs with huge risk, because you have already made the investment. What I am saying is that you should just make the production prototype with less features and ship that. Because that is how you go to market quickly, which is usually the larger point of such development.
This is also why Shenzhen wins over hackerspaces (which are also great btw) but that is another story.
For another example, I made this case:
https://www.makerfol.io/project/8ycrZ9t-case-for-the-dp30v5a...
This would also have not been possible without the printer next to me. I constantly had to print segments to see how parts fit. With a week-long turnaround time instead of ten minutes, I wouldn't even have bothered.
Sure, if I already know how to design and print, maybe I could have designed something without owning a printer, but even that is not very likely (I generally have to make alterations a lot). For $300 (and a bunch of time spent), it's a no-brainer if you want to get into the hobby.
Pick&place, as well as 3D printing, begins to make sense at industrial scale, with huge expensive machines. Sparkfun might be a borderline case, but I suspect even they won't use these cheap pnp machines in the longer term.
If you are a hobbyist or a low-scale manufacturing operation, you are much better off using MacroFab, PCBNG, Small Batch Assembly or AISLER.net for electronics production, and Shapeways for 3D printing (SLS). Alternatively, for quantities of ~10 of electronics devices, it makes sense to order your boards and stencils from OSHpark or AISLER, place components yourself using tweezers, and either use a modified oven or a hot air soldering iron for reflow.
This is speaking from experience (as a hobbyist/maker, electronics design engineer designing proof-of-concept and small-scale production devices, and https://PartsBox.io/ founder).