> Planck did not consider this a quantization, but merely a mathematical trick to be able to calculate the entropy of the oscillators.
My understanding was that Planck absolutely understood that his approach would have been a mathematical trick if he took the limit h → 0, but that in stopping at a nonzero small number he was explicitly aware that he was saying something peculiar about the energies in the system, and had strayed far away from that realm of pure mathematics into something that we would today effortlessly identify as quantum, even if that word did not exist at the time.