The simple-rules approach to strategy, mainly developed by Kathleen Eisenhardt, can be seen as a response to the dangers of over-rationality in the field of strategic management. However, the theoretical foundations of this approach are currently being challenged. The aim of this paper is to contribute to the debate on its theoretical robustness by mobilizing recent developments on the theory of “simplexity.” This work shows that it can be possible and relevant to respond to the complexity of an environment with simple rules. The first part of the article allows us to return to this approach to strategy. Its links with the theory of simplexity are then discussed. We show that simplexity offers a theoretical framework that can reinforce the relevance and interest of simple rules in strategic management. However, the use of simplexity also makes it possible to highlight the current shortcomings of the simple-rules approach to strategy and to consider ways to make it more dense. First, the issues of reliability, specialization, and selection still seem to be poorly addressed. Second, the notion of redundancy seems to have a different meaning in simplexity theory. Finally, the work of Eisenhardt and her colleagues still sheds very little light on the conditions for the emergence and renewal of rules, notably the role played by the strategic vision.