The R4 CQIF profile just includes an extension that points to a library and provides no guidance to implementers on how to extract information from an EHR to populate a questionnaire. (The only example for the profile doesn't show that - and is also broken, based on the definition of the extension.) As such, there's no mechanism for payers to reasonably look at the profile and have a clue how to appropriately create questionnaires that support CQL-based population.

The SDC IG, on the other hand, has many pages devoted to how to perform population, supports the same extension as the CQIF profile but also identifies the additional extensions needed to support population - and also provides additional extensions to guide supported population. It's much more appropriate for purpose. Bryn has already agreed in principle to remove the CQIF profile and point to SDC given that the CQIF profile isn't actually meeting its purpose and the sole example is broken.