Anti-austerity protests revived anti- and post-hegemonic sociopolitical imaginary, around the word. In Spain, 15M movement built the premises for political projects based on direct democracy and horizontal models of social organization, as defining features of the new muncipalists who won 2015 elections in several cities. The case of Madrid has revelatory value in the debate regarding outcomes of participatory innovations, as the alliance which pioneered digital democracy and multi-actor multi-level local governance lost elections of 2019. Although a relatively large body of research investigated the feasibility of democratic innovations by contrasting their designs and implementation processes onto the matrix of their objectives and underlying ideological principles, the literature explaining their outcomes is scarce. Few studies focus on factors modeling the sustainability of participatory democracy as city regime, and the most common approach stresses out neoliberal inhibitors, as structural breaks which limit the depth and quality of participation. The present study aims to contribute to filling this gap by extending the analytical framework to encompass factors related to horizontalism, as enablers of democracy innovations. It is concluded that while horizontal governance works as a spillover of inclusive participation, it is highly vulnerable to attacks designed to vertically restructure its working processes.