I find this misleading on several accounts.
1) Anyone can submit any junk they want to a journal and have it reviewed. This encourages people to submit papers that are incomplete and gives people false hope that such incomplete papers will increase their chances at MSTP admissions. Adcoms know this about in review papers, and as such I contend that the vast majority do not necessarily consider them as major positive notes on one's application (or positive at all).
2) The most important factors are GPA, MCAT, and research EXPERIENCE. I don't know what your undergrad GPA was, but a 33 MCAT is not so low as to preclude one from obtaining an interview. Combined with sufficient experience and some of the factors you listed in your later post, you may very well get an interview or acceptance to a top-20 program. I seriously doubt it has much to do with a submitted paper.
That being said, adcoms have varying opinions and one might disagree with me. I still don't at all agree with your assertion that an in review manuscript (or even a published one) is the key to being accepted to a top program. As for competitiveness of programs, it has only a loose association with ranking and I will again bash US News research rankings as an indicator of where you should attend. The idea of "top 20" being the most desirable is thus misleading to me. The MSTPs make up most of the top-50 USNews ranking schools (and indeed the ones that aren't usually have fully funded programs), and I would thus make getting into a top 50 program your priority.