As I understand it IK is a cause and effect function, you pull on the foot and the leg will follow. Carrara is capable of doing that through the use of hot points and adjustments in the range and motion. While the process is different from the one used in product like "Bones" the outcome is the same, move the foot and the leg follows. You definition of IK would only fit the "Bones" product so it is not a fare comparison. Poser for example is "IK compliant" yet you do not have to set a skeleton. Just my opinion, I could be wrong.