Welcome to the Serif Affinity Forums, @Mathewward.
The answer is the same because the reason is the same. Apple and Serif don’t share individual customer data, so (just as Apple has no way of knowing that you’re an Affinity Store customer) Serif has know way of knowing that you bought one or more of their apps via the MAS, so it isn’t possible to transfer licences between the two stores.
I fully share the frustration.
I will continue to use the Affinity suite, based on heavy investment of my time to master the product and find efficient workflows. Never the less, i think it is high time that someone at Affinity like a product owner / product manager really starts to communicate with the active user base (forum users), hear their voice about priorities, and provide a raw roadmap how to overcome the painful issues.
Still convinced that all Affinity staff is really working hard, never the less I‘m deeply dissatisfied with Affinity as a company regarding their autistic behavior and complete ignorance to well documented user feedback.