The benefit is stamplin.com gets insight on what people are viewing and reading. They get to see what the user sees. They can compile a database and use or sell that information to be used for marketing purposes.

Also, it's an "API" (looks more like a url poiting to a CGI program to me, but whatever). API's are "cool" and "fun", while running local programs that you have control over is old and boring and not the future of computing.