Template edits are tracked so that previous versions can be viewed. This paves an important way for merge requests. In the future, when a template is forked and modified, the new author will be able to make a request back to the original source to have their changes merged in; very similar in the ways that other services like GitHub or GitLab handle merge commits.
Recently, I've covered the implementation of this feature on Drifting Ruby. https://www.driftingruby.com/episodes/tracking-changes-on-action-text