Are frictionless experiences always beneficial? Customer loyalty consequences of Single Sign-On (SSO) onboarding

Retailers increasingly adopt Single Sign-On (SSO) to reduce onboarding effort and improve early conversion, yet little is known about how such frictionless entry shapes downstream retention and post-purchase behaviors. Using transaction-level data from 807,545 customers across 193 online apparel retailers, this study compares customers using SSO, password-based accounts, or guest access in their subsequent retention and post-purchase service behaviors. The results reveal a paradox of convenience. Contrary to what account-based access would predict, SSO users show roughly 16% lower repurchase odds than guest users who create no account, while password-based users show the opposite pattern with roughly 26% higher repurchase odds. SSO is thus associated with the lowest observed retention among the entry methods examined, and these associations become more pronounced over time. Both account-based entry methods are associated with higher rates of returns and exchanges, yet SSO users who engage in effortful post-purchase procedures show an attenuated loyalty deficit, a pattern consistent with the notion that retailer-hosted touchpoints may provide additional engagement opportunities for customers whose initial entry involved limited retailer-specific grounding. Furthermore, SSO users show little response to promotional incentives but react disproportionately negatively to unexpected costs such as shipping fees, suggesting that managing perceived costs may be a more effective retention lever than incentive provision for this segment. Overall, retailers adopting SSO should complement frictionless entry with light-touch engagement while managing perceived costs through transparent communication and proactive cost reduction.