It’s not about a single design team - it’s about a thirty year effort to make available ISAs / CPU designs that SoC designers can incorporate into their product

It’s not about a single design team - it’s about a thirty year effort to make available ISAs / CPU designs that SoC designers can incorporate into their products (sharing the costs of their development) and immediately tap into a wider hardware / software ecosystem. A large company could do it but do you really want to build your own LLVM backend? And the largest Arm customers do design their own CPUs. Of course RISC-V potentially challenges this model.