The question is how practical that mode of operation is on real network, or in other words whether it actually makes sense to run DOCSIS on network that can rel

The question is how practical that mode of operation is on real network, or in other words whether it actually makes sense to run DOCSIS on network that can reliably support that mode (think various xDSL technologies that can push >1Gbps over <100m of what essentially is Cat5 cable) DOCSIS is somewhat inherently asymmetric due to nature of the CaTV network. Even if the upstream and downstream channels would have same bandwidth, the upstream direction tends to have significantly worse SNR. Historically this was caused by splitters along the way, but also the cable modem is relatively cheap device installed on customer premises and thus has inherently lower transmit power and worse SNR than CMTS. This is the main reason why CMTS tend(ed) to have more upstream receivers than downstream transmitters.