I eventually learned that if you select a bunch of timeline steps and hit the delete key it will delete those steps - there's no prompt on the menu indicating that possibility. In that case the functionality exists and just needs to be added to the menu.
Additionally it would be very nice to have a "delete from here" menu item as well.
Additionally, the "find" feature doesn't work. At least I've never been able to find where a named feature within the timeline was introduced into the model.