Personally, I think the most interesting aspect about Mercerism in the context of "Do Androids Dream of Electric Sheep?" is the fact that, while it is a way to

Personally, I think the most interesting aspect about Mercerism in the context of "Do Androids Dream of Electric Sheep?" is the fact that, while it is a way to "emphasize humankind's capacity for empathy", as you've nicely put it, it is also constrained to the empathy box which is labelled as ones most prized possession and an extension of ones body in the book. Assuming the empathy box is merely an extension of ones self and using it requires obeying a relatively strict process (taking part in Mercer's "martyr walk"), what's left of you as a human being outside of it, is a biomechanical shell not much more capable or understanding of empathy than any android.