http://wccftech.com/how-to-switch-off-wi-fi-bluetooth-ios-11/

Apple may have tried to make things a little easier with its iOS 11 Control Center, but not everything was designed keeping the end user in mind. The new iOS 11 introduces a new “off-ish” behavior for Bluetooth and WiFi connections. For those of our readers who may be wondering why WiFi and Bluetooth stays on when they have turned them off in the Control Center, the toggles from the Control Center “disconnect” them from existing connections, but don’t completely turn them off.

Both the WiFi and Bluetooth will continue to be available, so user can stay connected to Apple services, including AirDrop, Apple Watch, Apple Pencil, and other similar products and features. An obvious security disaster considering how attackers are trying to infect products using WiFi and Bluetooth, the move has drawn criticism from both the public and security experts.