Yes, someone could be screened out without a holistic review. The bulk of people get a holistic review, but let's say someone applies with an extremely low MCAT and extremely low GPA (let's say a 22 and a 2.4) ... then they probably aren't going to get a holistic review. Just my perspective as a student.
With 5000-6000 people applying this year, some will get screened out but the bulk will go to Holistic review. Of those holistically reviewed, a large number (I think >500) will get phone interviews. Of those a good number will get in-person interviews (around 300 last year, probably the same this year). Of those, they'll pick 60.
It's all about reviewing as many people as possible to pick the most amazing ones (not just the ones with the highest MCAT or GPA, even if the school screens out the very low scores).
As always, feel free to ask any questions about the school, the first class, etc... if I can answer, I will.