The scale of being "tested" clearly convinced Meta (beyond OpenAI's scale) [0] HuggingFace [1], Perplexity [2] and unsuprisingly many others in the AI industry [3] that require more compute than GPUs can deliver.
So labelling it "untested" even at Meta's scale as a customer (which exceeds OpenAI's scale) is quiet nonsensical and frankly an uninformed take.
[0] https://www.cerebras.ai/customer-spotlights/meta
[1] https://www.cerebras.ai/news/hugging-face-partners-with-cere...
[2] https://www.cerebras.ai/press-release/cerebras-powers-perple...
[3] https://www.cerebras.ai/customer-spotlights