Regarding your first point, it doesn't even require the claimant to be better in any particular sense - it could be that their prior knowledge was simply a better fit to the new concepts.
Regarding the second, I don't think it makes sense to consider "difficulty in learning Haskell" to be "difficulty in learning all of everything anyone's done with Haskell." Even SPJ has (or at least recently had) a pretty shallow understanding of Kmett's lens library. The two important questions are 1) how much do I need to learn to get things done in Haskell, and 2) how much do I need to learn to participate usefully in the Haskell community. 1 is less than 2, which is less than what you described.
"There is more stuff to learn that can make you even more productive, but you can get by without it and still be productive" often gets treated as a negative, and I find that strange...
Regarding the second, I don't think it makes sense to consider "difficulty in learning Haskell" to be "difficulty in learning all of everything anyone's done with Haskell." Even SPJ has (or at least recently had) a pretty shallow understanding of Kmett's lens library. The two important questions are 1) how much do I need to learn to get things done in Haskell, and 2) how much do I need to learn to participate usefully in the Haskell community. 1 is less than 2, which is less than what you described.
"There is more stuff to learn that can make you even more productive, but you can get by without it and still be productive" often gets treated as a negative, and I find that strange...