It's an administrative task, to be sure. The possible shortcomings causing rejection, however, are not just an easily fixed "you missed a section" but also not having data for a required section. The latter problem can range from the data simply not being in acceptable form (likely fixable) to not having that data (potentially problematic).
(Most applications being accepted is not surprising, and chances of a well-run biotech or pharma not having collected necessary data is low. But this is our first regulatory approval submission, and we did have CRO data issues.)