'Newest topic' option sorts topics by the timestamp of when topics were created. The timestamp is not displayed in UI and, in fact, it cannot be found easily in View history(there is no direct reference to the event of creating a topic).

A timestamp under the topic title refers to the last update on a topic, and it might be confusing for a user to see topics sorted by 'Newest topic' having various timestamps not reflecting the time of topics' creation.