What is going on with the PCB? It looks like the soldered several dev boards to a big PCB. I can't think of a good reason to do this.
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Not only would designing a fully custom board require a lot of error-prone effort, getting a lot of components in tiny quantities can be prohibitively expensive.
Good engineering includes optimizing for cost (monetary and non-monetary), and I'd argue that for many hobbyist one-off projects that won't be manufactured at scale, dev-boards-on-PCB is good engineering.