I wonder what is happening behind closed doors for these companies to be issuing such a joint letter.
NVIDIA sells the tools. The more the better it is for them.
Microsoft and Meta are also-rans at this point. Their best hope of catching up is probably leveraging their infra and open models.
Nvidia is subject to export restrictions on GPUs to China. So Chinese labs have responded by allowing American hosts to run their open-weight models in the US, where there are no restrictions. We see this in the EU too where Scaleway, and now Hetzner are getting into the inference host space serving Chinese open-weight models.
So Nvidia benefits from more inference providers running many Chinese models that they otherwise would not have been able to service.
Almost certainly these companies are using similar strategies as the Chinese models which they fear will be made illegal.
It's also the case that it makes it hard to attract customers if your openweight model is banned. A major reason the likes of Qwen, Kimi, GLM, and Deepseek are popular (well, at least highly talked about) is because of the open weight models they gave away.
They've seen the government officials parroting OpenAI and Anthropic lobbies talking points, and they have smart enough people to see the signs of upcoming regulatory capture.
If I were cynical, I'd say it isn't helped by the current US administration.
Different companies have different motivations. I'm sure some are genuine, but a lot of them simply lost the race (to OpenAI/Anthropic/Google) and know they can't compete anymore, so are shifting strategies. How many times has Microsoft done exactly this in the past?
If there are effectively only two AI companies allowed to train or run model inference then demand for hosting, GPUs and data centers goes down, so they'd be able to squeeze their suppliers that much more too.
They are worried about OpenAI and Anthropic making their own processors and controlling the whole stack is my guess.
Nvidia benefits no matter what because their hardware is being used. Microsoft and Meta benefit by making sure that the gap between "Anthropic/OpenAI" and "everyone else" doesn't widen, or they'll be hopelessly dependent on those frontier labs.
Probably the fact that they don't want Anthropic or Google or OpenAI to have access to their data theoretically, and that they do want to use good AI, and that they don't want to spend the money themselves to make a good model...
Probably a real effort to push for some kind of sanctions or commerce block on Chinese models. Anthropic just doubled their political spending to $40 mil for the midterms to push for "AI Safety."
The future will probably have most of all companies running local models, simply because the alternative would be essentially every company that uses LLMs ending up becoming completely dependent upon Anthropic et al. And that dependence would be milked to the point of absurdity once solidly established.
And as a more general point - more major competitors in a domain is very good for everybody except those competitors themselves, who would rather there be as few as possible.