The Research Excellence Framework is the mechanism through which the four higher education funding bodies allocate funding to higher education institutions. It is meant to reward those institutions doing the best work with a greater proportion of the funding pot with which to do a greater volume of work in the hope that the quality will be unaffected. A meritocracy then.
When it comes to data, 'open' is mainly a licensing approach. Open release can amplify the utility of a dataset, but it tells us nothing about the quality of the data or the processes that went into its production. Those are technical features of the dataset, unaffected by the legal conditions for re-use.