The other thing is, that the location of the boats at that time, made this platform handy for loading and handing the boats.
Here are some more images of that area. I had to go through almost 1200 Flush-decker images I have scanned. But first a short history of the alterations to this area on Flush-deckers.
As built there were variations between yards and as changes were made to "improve" the design. But, they universally had only one searchlight aft of the stacks.
Sometime in the early 1920's, the USN altered the searchlight platform to have two searchlights and this platform.
Starting in 1927 and by 1930 or so, the USN altered surviving active duty units returning to one searchlight on the searchlight platform. And then at some point, that platform one level below the searchlight platform was shortened to only under the searchlight.
Leading up to the US entry in and during WWII, there multiple changes going on. The searchlight platform was replaced with a all new platform that could support at first three 50-cal MGs and then one or two 20-mm guns.
Note on the first two images that this platform isn't very robust, It never would be able to support a larger caliber gun. And it appears that the platform deck is largely empty except for items being stowed there. I now don't think that con station equipment was located in this are or under the searchlight.
In this photo dated in June 1927, the number of searchlights has been reduced to ONE, but the lower platform is still there. Note that the crew has stowed a work boat on the platform.