The security benefit is centralised control rather than convenience. When an employee leaves, disabling their identity-provider account removes access everywhere at once — instead of hoping every application was included in an offboarding checklist. That single property is why enterprise buyers treat SSO as non-negotiable.
For a SaaS vendor, SSO is usually the feature that unblocks enterprise deals, and it is more involved than it appears. Supporting SAML and OIDC, handling just-in-time user provisioning, mapping identity-provider groups to application roles, and testing against providers that each interpret the specification slightly differently is weeks of work, not days.
Codazz builds this in production — Authentication & SSO.