No, it's still O(N) amortized. Imagine if the hashmap doubles in capacity whenever it is full or hits its max load factor. Then you end up having O(N) copy operations. O(2 * N) = O(N)
While your objection stands, repeated trainings of a hash table can be very impactful on the actual walltime spent, and it is a bad benchmark not to include the optimization of preallocating.