Where are the calls for cable companies to downgrade their traditional TV channels (set top box) from HD to SD so that they can re-provision some of the bandwid

Where are the calls for cable companies to downgrade their traditional TV channels (set top box) from HD to SD so that they can re-provision some of the bandwidth toward internet? I don't know enough about the tech to know for sure that this is possible, but it seems likely since it is the same wire and they offer different levels of TV and internet service. If I'm right and it is possible, why is it that only streaming providers are being asked to sacrifice the quality of their service?