There are two main reasons: one mission-driven, the other practical:  Mission considerations: PLOS has always been deeply committed to reforming and reimagining the current practice of research assessment to focus less on individual proxy metrics for impact and more on the actual contributions of authors to research. Focusing on corresponding authors – indeed, building entire business models around their designations – further reinscribes the privileged position of corresponding authors, ignoring both the contributions of other authors and the benefits they receive when publishing.   Practical considerations: Including contributing authors in the model is a key step to highlighting their roles in the research process and ensuring institutions are covering that cost.  By including contributing authors, the PLOS Community Action Publishing model begins the process of integrating so-called “Read” institutions into “publishing-based” models. Institutions that are affiliated with contributing authors but never corresponding authors “exit” business models focused on corresponding author designation. Their money goes with them.  Given the well-articulated concerns about the shift-to-OA placing undue burden on research intensive institutions to carry the costs for all academic publishing (while read institutions read for free), finding novel ways of integrating these institutions fairly is an important step in evolving business models.