[amelius]

It's not the PCB that is hard. It is interfacing with all the interface ICs, each having their own quirks and proprietary drivers, etc. At a certain point, reading data sheets becomes like filling out tax forms, extremely boring work.

[jandrese]

That assumes you can even get access to the documentation. Some vendors are very bad about not giving up the necessary documentation to develop drivers, especially if you don't speak Chinese. Or they demand you sign a NDA before you can read the docs, and aren't interested in even talking with you if you aren't about to buy at least 150k chips in your initial order.