You're definitely right that there are certain things under an applicant's control - GRE/GPA, SOP, etc. By all means, make your application packet as strong as possible, and use all the resources you have at your disposal to do so.
I wasn't trying to say that the entire process is all chaos and that your chances are completely random. My point was more about how some applicants approach specific programs. An applicant can do certain things to make their application broadly more attractive to all schools (do research work, go to conferences, etc) but when it comes to a particular program, there is no "special sauce" for getting in. A number of users here have been laboring over tactics to get into specific programs, and there's just too much going on to reliably predict whether or not this or that tweak will get you into that program.
In short, most of the applicants on gradcafe are already aware of the general types of things they could do in order to make a more attractive application. All programs, no matter what their rank, are looking for basically the same criteria. It would be an error, however, to attribute one's getting into any one particular program directly to something in their application packet. (e.g. You might have a great application that is worthy of getting into some of the CHYMPS, but there's no guarantee that that packet will get into Harvard in particular).