Nobody has to "run their own setup". Just buy inference from one of the many different open weight inference providers out there. You can use non-chinese ones as well if you don't trust Moonshot AI.

At this point, the only reason why Anthropic has an advantage is laziness on the deciders' side (of which there is a lot) and, for non-coding work, the Claude harness is significantly better than most alternatives. For coding there are several model-agnostic alternatives on par or better than the frontier labs' own offerings. But arguably that is not yet true for office/document work.