I take a different view of the solution, yes I agree if an open access operator spots a profitable gap, then there is revenue to be had from potential new passengers.
However what I disagree on, is why the DfT specification has to stay as it currently is, unreviewed and unchanged, and the state owned operator cannot do that new service, instead of running a virtually empty train somewhere else by reallocating resources (reallocating to cut subsidy, not adding to subsidy needed). Some parts of the DfT specification seem to be bogged down in a service level from years ago even if the world has moved on.