I'm thinking probably Intel themselves invested money into their own engineers to power optimize their hardware for Linux (arguably too little too late considering the inefficiencies of CISC-to-RISC in hardware and the growth of ARM as a result). Surely they would do it for servers (big electricity costs for buyers), there may be some overrun into other form factors.
I guess there will always be these kinds of momentum-investment issues (need users for investment, need investment for users), for smaller players, generally speaking.
