Given the nature of the phone hardware, would it be easier to develop a phone architecture from the ground up rather than trying to reverse engineer the existin

Given the nature of the phone hardware, would it be easier to develop a phone architecture from the ground up rather than trying to reverse engineer the existing phones? For instance, wouldn't it be easier to start with a power efficient, battery-powered SBC and then add on components needed for a phone rather than trying to reverse engineer a whole bunch of binary blobs and run into issues with DMCA etc?