Microsoft is deeply entwined in OpenAI and has obvious reasons to dogfood, yet their people are using Anthropic solutions.
Valuation behemoth OpenAI has been forced by the market to use Anthropic standards a couple times, having no comparable solutions of their own.
… I can see it.
Anthropic's marketing somehow punches hard. Not sure why, but the stuff they do sticks. Not because the products are great, but because the way they communicate about it gives people the right feeling. They do have legitimately the best coding model now for most tasks, and for narrative prose, but the marketing stuck and people stan'd them even when they were trailing.