I'm sure one could just as easily say that getting the mail is like other addictions, because I chronically get excited at the thought of my latest online order arriving.
There actually are many people addicted to shopping. You can often see them on “Hoarders” or similar TV shows, their homes filled to the brim with products in boxes, unopened.
I do feel the analogy is overused though, mostly because the notion that chemical reactions in the brain are involved seems to have an unduly strong impression on people, whereas I imagine that these phenomena in the brain turn up in all sorts of human activity (see sandworm101's comment).
There's also a negative connotation that exists with drug usage. I could be totally addicted to jogging, though ("runner's high"), with an almost totally net positive effect on my life.