Platform companies, represented by“Taobao,”have formed a unique business model that is vastly different from traditional enterprises through continuous innovation and exploration, especially the evolving profit model based on a free pricing strategy, which has led to a surging wave of cross-border transformation of platform companies. Existing research mainly explains in the perspective of asymmetric pricing for two-sided users why platform companies provide technical services to users for free, but fails to explain why platform companies offer services to both buyers and sellers for free, and ignores the important question that“how are scarce resources in the technology service market allocated when the market price is zero?”This paper revisits the“free-profit”model of platform companies from the perspective of resource allocation. By studying their development and evolution process, it is found that“exchanging services for traffic, and then profiting from traffic resources" is the common logic for platform companies to achieve“free-profit ” through service upgrades, version stratification, and cross-border collaboration. By theoretically deconstructing the internal value creation process, it is discovered that the effects of total expansion, structural optimization, and efficiency enhancement effect of market transactions formed by the aggregation of user traffic resources are the profit sources for platform companies. By theoretically analyzing the supply and demand decision-making process in the free technology service market, it is found that the allocation of scarce resources in the platform companies’technology service market is driven by user traffic and data; and compared with the traditional market price mechanism, a demand-centered supply optimization, as a more efficient way of resource allocation, has replaced price-centered supply and demand mutual adjustments. Government departments should change the traditional price-centered paradigm of market regulation, explore new types of regulatory methods suitable for the“free-profit”model of platform companies, regulate the traffic competition between platform companies, and establish and improve the data trading market system so as to further unleash the efficiency potential of resource allocation in the field of digital economy.