Some networks charges high in cellular data...so disability of background data is great money saver.
Step 1 Open Settings and tap Data usage.
Step 2 Scroll down to view a list of your Android apps sorted by data usage (or tap Cellular Data usage to view them). Tap an app to check out detailed usage statistics. This is where you can restrict background data for individual apps.
Step 3 Tap the app(s) you don’t want to connect to mobile data and select Restrict app background data.
I could not find a single setting to Disable or Restrict every app's background Data Usage, I can find setting to restrict All Background Data and one to Disable Data altogether, using only Wifi now.
You should see the data restriction if you're on Android Pie, if you want to set restrictions on earlier versions you can use apps like NetGuard to restrict data to apps.