The point is not the difference between a fake memory and a real one (let’s grant for now that they are undistinguishable) but the fact that positive experiences are worth a lot more than just the memories they leave you with.

I may not know the difference between a memory of an event that I experienced and a memory of an event I didn’t experience. Looking back on the past, they’re the same.
But each moment of pleasure that I only remember, without having experienced it, was essentially stolen from me. Pleasure is a state of consciousness and only exists in the present.