During the 2014 Gaza war Facebook became a central arena for moral/political boundary work for Israeli users, resulting in unusually high rates of politically motivated tie dissolution. Cultural criteria were thus applied to restructure and symbolically cleanse social networks. We analyze Facebook’s visibility-structures, interview data and public posts to explore this phenomenon. Studying Facebook interaction reveals cultural mechanisms used offline to sustain heterogeneous social networks and facilitate interaction despite differences—group style differentiation between circles, differential self-presentation, and constructing imagined homogeneity—whose employment is impeded by Facebook’s material design. This case of materiality-informed value homophily introduces materiality to the sociological understanding of the interrelations between culture and network structure. Interviewees reported dissolving ties following their shock and surprise at the political views and sacrilegious expression styles of their Facebook friends. We demonstrate that their shock and surprise derived from Facebook’s design, which converges life spheres and social circles and thwarts segregation of interactions, group styles and information. Rather than disembedding individuals from groups within the ‘networked-individualism,’ it makes individuals accountable for their statements towards all their social circles. In dramatic times, this collapse of segregation between life-spheres, affiliation circles and group styles conjures Durkheimian sociability and symbolic cleansing despite commitment to pluralism.