My users have Windows 10 rugged tablets with a pen-interface and fingertouch disabled by the It-department.
That makes it impossible to zoom on the map as you don´t have a scroll-wheel on the mouse or pinching with the fingers.
As windows 10-tablets have big screen it would be possible to add two buttons +/- (similar to the widget in a webmap) without making the map to small.
On iOS and Android a zooming widget would decrease the available mapspace and is a bad idea.