OpenAI actually does have two excellent OSS models. Not Anthropic. Not that OpenAI is 'open' per se, but more so than Anthropic. Also see the Codex vs Claude Code extensibility.

They are far from excellent and they were open sourced due to the mounting pressure for calling themselves "Open" AI and not doing anything open. At the time, they also had Chinese competitors wiping the market value of many stocks (NVidia, etc.) after releasing true OSS models that performed as good as SOTA models and they had to retaliate. I don't know of anyone who uses those OSS models in production instead of Qwen series or DeepSeek.