A deliberate scope, not an absence of one
Anonymous access permits a specific, narrowly defined action without requiring the requester to have any established identity — browsing a public catalog, submitting an inquiry, viewing published content. Designed deliberately, it represents a conscious decision about exactly what unauthenticated parties may do, bounded tightly enough that the absence of an identity doesn't translate into broad, unaccountable capability.
Guest checkout applies the same idea to completing an actual transaction without a persistent account: the necessary authorization is scoped entirely to that single transaction, trading the ongoing relationship an account would provide for lower friction at the moment it matters, without leaving standing access behind once the transaction completes.
Where the scope quietly widens
The recurring risk is treating 'no identity required' as equivalent to 'no limits apply,' which tends to happen gradually rather than all at once: an anonymous path built for one narrow purpose accumulates new functionality over time, without anyone explicitly revisiting whether each addition still belongs behind an unauthenticated boundary. What started as a deliberately scoped exception can end up, feature by feature, considerably broader than anyone would have approved if asked about it directly.