I'd guess because it's primarily controlled via config.local.php in the $config array.
Actually, it's not controlled by them. It stores Storage Driver in database as settings object and the S3 SDK version is too old, not working properly on latest regions and authentications.
I guess the team no longer maintains the storage driver.
I had tried to use latest version of aws sdk via custom addon, but the storage driver is initialized before addon loaded.
so I could not use it without editing core files.
If cscart supports S3 as storage driver, it would be super easy to deploy code to multi WAS under load balancer.