The "build vs buy" debate is crucial for founders and engineering leaders when deciding whether to develop non-core components like Single Sign On (SSO) or Directory Sync in-house, or purchase existing solutions. Key considerations include the learning curve for engineers, opportunity costs of diverting resources from core product development, ability to keep up with customer demands for new identity providers, long-term maintenance requirements, and availability of support when faced with technical challenges. WorkOS is an example of a solution that can be purchased if in-house development seems unfeasible or too resource-intensive.