Current cable modems can negotiate with the CMTS to determine which of several channels to use for communication, even when channel bonding is not in use. This means different customers can be communicating on different channels if the CMTS has sufficient resources. Are you saying that this was not possible with DOCSIS 1.0? Obviously it is more common for channels to be shared than for each customer to get dedicated channels, but I don't think that is a technological limitation.