I feel like that argument is flawed. I cannot think of another good example (I am sure there are plenty!) but there is a big difference for discoverability between:
A function that does something *different* and functionality does not exist in a built-in (or whatever namespace you are considering). For example, zip_longest v.s. zip: if you have know/expect one of your iterators to run out early, but do not wish the zipping to end, normal zip won't do and so you will end up searching for an alternative.
A function that is a "safer" version in some "edge case" (not extra functionality but better error handling basically) but that does otherwise work as expected is not something one will search for automatically. This is zip versus zip-with-strict-true.
I did not phrase that particularly well, but I am hoping people get the gist/can rephrase it better.