Not to sound like a jerk, but I've always wondered what people mean by this.
Simple: It's tiring/time consuming/boring in comparison to other things I could be doing which would advance my cause faster. I know there's a better way, it won't take that
much time and money to get it running, and my time is better spent either advancing new designs, working on infrastructure, or actually enjoying the fruits of my labor.
What I mean by "better way" is stenciling/reflow vs manual SMT soldering. I took both of Sparkfun's SMT classes (stencil vs manual) and left with absolutely
zero doubt that stencil/reflow is the way to go, but also with absolutely zero doubt that even it would irritate me without a jig to stabilize my hands for component placement, so I'll try to build a "manual pick and place frame" (rail table with a vacuum pen and probably a USB microscope) and give it a go with the good old toaster oven/hot plate.
I can understand not wanting to do it, since it's boring.
No, that is
the best reason. It's boring and time-consuming. Sure, I could gut it out and do it by hand, but pretty much every accomplishment in my life I've been proud of has originated from having a task that was too boring and finding a better, more efficient way to do it. Faffing about with rice-grain sized components and tweezers just isn't acceptable for production (maybe not even prototyping). If I didn't know it was a massive time sink, I'd throw my hat in the DIY Pick and Place scene, but honestly between the day job and anything resembling fun, I can only embrace semi-lost causes, not actually lost ones (it's not actually lost; I have faith there'll be a good OSS PNP machine eventually, but I have enough new things to learn right now).