By default (DefaultSettings.php), wgNamespacesToBeSearchedDefault only includes NS_MAIN
In initialize settings, wmf sites are set to have NS_MAIN (0) as true (1), and then namespaces 1 through 13 as false (0). Individual sites set additional namespaces to be false, despite those namespaces never having been included in the namespaces to be searched. These entries are extraneous and should be removed, both for code readability and because they unnecessarily bloat the size of InitialiseSettings.php.