That story is hilarious.
I think it highlights how difficult it is to even discuss these things. We're all using different definitions of "good" and "mastery" and "7/10" and "10/10".
Being able to adapt and pick up new things at a 7
level though - is the real FSD
This is a really interesting line of thought.
By my definition, I actually don't think this is possible, at least not for larger languages/tools/frameworks.
My reasoning is this. To be a 7 (my definition) requires time. You need to not just understand the basic premise and syntax of a language, but you need battle scars. You need to have shipped some code in that language, gotten familiar with the ecosystem of libraries, you've troubleshot production issues, and become familiar with common pitfalls and how to avoid them. You've checked out some large codebases in that language and gleaned best practices and things to avoid. You have probably also spent some time in that community, watched/attended presentations from recognized leaders, and have a sense of which way the wind is blowing.
Everything I just described takes time. I don't think even the smartest person in the world can drop in and achieve that immediately unless we're talking about a relatively simple tool.
I mean, could somebody who already knows CSS pick up TailwindCSS and be a 7 quickly? Absolutely.
Could an engineer who is new to Ruby/Kotlin/Python be a 7 quickly? Not by my definition, not by a longshot. In my experience, seasoned developers drop into existing codebases in these sorts of languages and make a mess of things at first until they get used to the ecosystem.