I have to wonder if it's because of how many Enterprise customers they have who have standardized on Github Copilot and gotten it through the gauntlet of legal approvals etc.
We're putting other providers through the gauntlet. An M4 Studio or two running the latest Qwen3 or whatever counts for state of the art in open models is also looking a little more viable all the time.
Having some open weight deployment or vendor is also a good thing, because you may have domain specific tasks where you can get better results on domain specific problems with a quick finetune.
Unsloth makes it particularly easy. Open weight LLMs are incredibly powerful building blocks.