Interesting take on the academic nature of DDD. We talk a lot about "Ubiquitous Language", but very little about the mechanical sympathy needed to run an event store at scale. If we ignore the engine's internals, we’re just building another layer of "magical" infrastructure that will eventually fail the domain experts when throughput increases.
One of the best and safest methods in an immutable event store is to store sensitive data as a reference. Some purpose-built event stores offer such capabilities by design.