Presented at 2024 INFORMS/ALIO/ASOCIO. June 19th 2024, Medellín, ColombiaAbstract:In this article, we argue, based on consolidating learnings from project practice, that mechanisms and subsystems being implemented for Digital Infrastructure, which are multi-stakeholder in nature, are to be as complex as needed to encode a variety of behavior, but as simple as possible in order to provide legibility for its affected and regulating stakeholders. Both of those goals can be read as an interpretation of the Occam's Razor and Ashby's Law of Requisite Variety heuristics over a Models-Based Systems Engineering workflow. Together with the Precautionary Principle, we summarize the base set of decision principles for Mechanism Selection into three: Variety, Legibility and Safety. Then, we proceed to provide two case studies on which those principles were actively applied: one around the selection of the Aztec Blockchain Sequencer Selection Protocol, and another on the ideation and implementation of Neural Quorum Governance on the Stellar Community Fund.