3 Col Elgg River

Question: on 3 Col Elgg River Sidebars.

Presently I see that right sidebar can be activated with JQuery Local Ads Rotator Right Sidebar. But there is a Left Sidebar as well which is by default dormant. My Question is is there a good reason for left side bar to be disabled by default. 3 Column River Activity Plugin at https://elgg.org/plugins/844663 or River Add ons can activate the left side, and can open up opportunity for content display on left side as well. However, I don't see any active work or work in progress for doing such so wondering if its left dormant for some reasons.