outline-view widget factory or injecting a singleton widget

[cwyark]

Hello, I'm new in theia community, hope someone can help me to understand theia how it design ;-)
I'm curious about why outline-view widget is created from factory when every update, not injecting a singleton widget and get this widget from widget manager ?

theia/packages/outline-view/src/browser/outline-view-service.ts

Line 24 in 6959b6a

export class OutlineViewService implements WidgetFactory {

Can we create a widget like this steps ?

bind(MyWidget).toSelf();
bind(WidgetFactory).toDynamicValue(ctx => ({
    id: MyWidget.ID,
    createWidget: () => ctx.container.get<MyWidget>(MyWidget)
})).inSingletonScope();

Then just update the root node when every refreshment.