I don’t think we will have a system in which we can only increase the DSR. Ultimately it has to be funded by the Stability Rate.
Having the Stability Rate solely based on risk, and using the DSR to absorb supply only works until the DSR needs to go higher than the Stability Rate. At this point we have to increase both together (adding the DSR component to the Stability Rate) to keep the system solvent.
I agree the Risk Premium should be set solely on risk, and that the other components, DSR + Governance Fee + Oracle fees should make up the rest to the current ~19% rate that the market is willing to pay. This works fine if demand is uniform across collateral-packages.
However if demand is not uniform, then we may want to use specific increases to the Stability Rate for a particular collateral-package, in order to prevent the negative effect the DSR funding component has on other packages.
This is largely a terminology problem, the technical lever labelled ‘Risk Premium’ can (but doesn’t have to) include two components: the actual Risk Premium and a Collateral Specific rate modifier to counter demand.