I was going to reply that Anthropic, which supposedly is the most capacity constrained of the leading AI labs, still provides access to models as old as Opus 3.

But then I realized Opus 3 is an outlier, and Anthropic has removed access to relatively more recent models. https://platform.claude.com/docs/en/about-claude/model-depre...

I wonder what the deal is with Opus 3.

I believe a lot of people prefer it for "creative" writing.