ASWebAuthenticationSession Async/Await API

Is there any particular reason why ASWebAuthenticationSession doesn't have support for async/await? (example below)

do {
  let callbackURL = try await webAuthSession.start()
} catch {
  // handle error
}

I'm curious if this style of integration doesn't exist for architectural reasons? Or is the legacy completion handler style preserved in order to prevent existing integrations from breaking?

ASWebAuthenticationSession Async/Await API
 
 
Q