You're missing the obvious. Time. There are highly talented developers who have the technical ability but had no time in the past to do these things because of real life obligations besides their job. Many are producing 10x more valuable output now. Also you're missing that Anthropic as a leading frontier lab isn't a good comparison for almost any metric for any other company in the world. It defies any principles companies usually have like unlimited talent supply.
To wit, I'm not producing 100x or even 10x more valuable output, I'm producting <infinity>x output now. I've gone from "no time/will to push through personal projects" to actively working on 5 in parallel, just because I only have to do the broad design and UX development now.