Yeah spot on - exactly what I was aiming at too...
Having the intuition to use reverse (& pragmatism to keep it simple) is a great sign, and realistically more valuable [to me] for hiring than implementing rudimentary algorithms, but... still want at least a bit of both abilities
Also knowledge of standard library / language features is useful but (for me) doesn't equate to abilities in complex problem solving.
But honestly could be bias :)
I usually even say that they can make up library APIs if they want, because I don't really care if they have memorized the python stdlib, I just want to seem them think about and work on a coding problem.
kind of organically landed on a similar thing, where initial task is kept pretty simple (but not covered by common libs)
Some folk solve and code this quickly, so we add a requirement. (Generally up to a few stages - think like Advent Of Code)
Any leftover time can be spent discussion wishlist items for productionising, optimising, tests, etc..
But: plenty of people only complete the first stage, but this can absolutely be a pass too (based on comms style, approach, etc..)