You can still build interesting devices that are not available off-the-shelf. It's just that these days most of the value (and complexity) lies in the software, not the hardware, and people are both not capable of writing complex software and do not enjoy doing it.
As an example, take a Nordic nRF52832 in a module, connect some sensors or LEDs to it, and you have a pretty neat device that you could access with your phone. But programming it to do something is an entirely different story.
As an example, take a Nordic nRF52832 in a module, connect some sensors or LEDs to it, and you have a pretty neat device that you could access with your phone. But programming it to do something is an entirely different story.