The peer widgets seem to have many differing properties. Compare the two AlertDialog widgets. You'll see they are very similar, but not at all the same: https

The peer widgets seem to have many differing properties. Compare the two AlertDialog widgets. You'll see they are very similar, but not at all the same: https://api.flutter.dev/flutter/material/AlertDialog-class.html https://api.flutter.dev/flutter/material/AlertDialog-class.h... https://api.flutter.dev/flutter/cupertino/CupertinoAlertDialog-class.html https://api.flutter.dev/flutter/cupertino/CupertinoAlertDial... My guess is there were enough widgets with enough differences in behavior or features that they abandoned a theming approach.