True. But speed-wise, that is about as slow as KNN, because you have to smooth across all of the dimensions. Of course, the slow part is the adding data, not so much retrieval, unlike KNN.
Actually, I'd say it's somewhat slow on both adding data and retrieval. It's checking adjacent bins in all dimensions for adding and retrieval, leading to <math>2^n</math> entries checked for each operation, where n is the number of dimensions. If anything, retrieval is a bit slower, because for each entry you need to process all guessfactor bins, whereas for adding data you only need to process guessfactor bins near the hit.