How Commit works in a transactional push replication with updatable subscribers
To paraphrase the quoted block, with immediate update the only guarantee is that the commit is immediately updated to the publisher.  The changes will be sent to the other subscribers in due course.  

Without immediate updating, your changes are only committed to the local subscriber, and queued for distribution back to the publisher, and following that, the other subscribers.

In both cases there is a period of time when a stale record is still at the other subscribers, and one of those subscribers may update the stale record and cause a conflict.