One reason is that I feel I spend more than I would if I just bought a journal. Another is that I end up not using the journal anyway; and most of the time they don't look good.
I'm sitting here at CBTL, though, with a stamp pad.
If you get all 12 stamps by January, all the proceeds of the coffee you bought go to a foundation that supports scholars.
So yeah, I think I'm getting that journal. You might want to consider it, too.