Massive open online courses (MOOCs) are now well-established as a highly effective, flexible and large participation capacity distance learning tool. They have enabled unprecedented access to educational material for millions of people worldwide, however, still suffer from significant student non-completion. Various theories have been proposed but we still lack a comprehensive understanding of why such attrition occurs. Herein we have analysed data from all MOOCs offered by the University of Exeter (UK) in 2018 in order to investigate whether "Social Learners" (i.e. those which comment on MOOC forums) exhibit differential non-completion than "Non-Social Learners". Results demonstrate that the former are considerably more likely to complete MOOCs, with median steps (i.e. "click points" within each MOOC) accessed (as a percentage of total steps) for Social and Non-Social Learners ranging from 50 to 100% and 9-46% respectively. In addition, the number of Non-Social Learners enrolled onto each MOOC was consistently greater than the number of Social Learners, with ratios of Non-Social Learners to Social Learners for each MOOC ranging from 1.75-11.30. Results therefore suggest that whilst Social Learners are in the minority Social Learning is an important tool to prevent student attrition. More research is therefore required in order to further understand the multifaceted value of Social Learning (i.e. technical vs purely social) in order to inform future MOOC design to maximise such benefits for students.