As of today, the item data history is maintained for publisher data only. This means when Subscribers view the history of an item, they can only see the original data from when the Publisher created the item, and whatever change was most recently made by the Subscriber themselves. Subscribers cannot see any of the changes made in between the creation of the item and the most recent edit.
This feature would extend the functionality to capture item data history for subscribers, therefore showing a complete list of all item history.
This, indeed, is needed to be able to capture the full trail of changes on an item. We will evaluate its alignment with our product strategy and roadmap priorities.