I mean, yeah, why not? You take a bunch of off the shelf boards and put them together on the PCB as is. To make a PCB with all of the components on it would not be very DIY. That's a custom board and out of scope for DIY.
This is also a hobby project. To custom build a PCB with all of the components brings this into the Kickstarter world of something. So the person can buy <5 PCBs to play with as hobby or attempt to fund say minimum 500-1000 pieces. From TFA: "Important Notice: This is just a fun project, it was started to pass the time, it is not at all professional and is not intended to be. Is not an alternative for professional device."
Even with the method chosen, if you think the person did not become better after making the simple PCB or any of the other coding required, you're off your rocker. Every build like this comes with mistakes and learning how to correct them.