What functionality is missing? What is unsatisfying with the current situation?

Unlike in maps, chronicles do not seem to have a way to add pins to groups in order to hide/show numerous pins at once. This leads to the map associated with a chronicle, especially for a large chronicle, to end up looking very cluttered over time.  

How does this feature request address the current situation?

Adding groups to pins for chronicles, similar to what is available on maps, will help to keep things clean. Alternatively, it could be linked to having a timeline shown/hidden and match the pings associated with events in that timeline, hiding or showing them when hiding or showing different timelines.  

What are other uses for this feature request?

This would be a single use feature, but would hopefully be easy to implement since a similar feature already exists elsewhere.