Spiderfication is a mechanism to reveal co-located markers. Like passengers at a bus stop.
Click the ADD PASSENGERS button on the map to see spiderfication in action. A single click or tap on a route stop (which is a cluster marker) causes the passenger markers to spiral around their shared location. Without spiderfication you would not be able to click on the individual passenger markers and see their balloon info, because, being in the same location, they'd be stacked on top of each other and appear as a single marker.
Spiderfication and clustering do not seem that useful for single markers, at first. But when you need to visualise clusters and cluster aggregations in a uniform manner, then the feature of clusters of one starts to make sense.
The allowClustersOfOne attribute, unique to RegionBound, brings consistency of appearance and consistency of information to your maps.
Without this feature, after clicking ADD PASSENGERS, the marker for the route stop with 1 passenger would display as a single passenger marker, rather than a route stop marker. This would be inconsistent and confusing.
Clusters of one play an even more important role when, in addition to counts,
your clusters are configured to display aggregation results.
Without allowClustersOfOne these aggregation results would not be visible on single markers at all.