Well, first of all this is for an IoT CPU, so there will probably be less competition there and it can probably be tuned to specific niches. But I have to disagree that building a new CPU is easy. This is only true if we're talking about "toy" CPUs like some of the RISC-V implementations put out by UCB undergrads, these run at ~200MHZ clocks and with sub-1 ILP. If you want to make a high end and energy efficient CPU, it's still quite a difficult task and most novel CPU projects (e.g. the Mill, I guess the Adapteva Epiphany might count, although it's not really a CPU) don't have an existing GCC/LLVM backend.