Background draw is it real required?

Any watch face created via VSCode wizard contains drawable Background.

With simple code like

    function draw(dc as Dc) as Void {
        // Set the background color then call to clear the screen
        dc.setColor(Graphics.COLOR_TRANSPARENT, getApp().getProperty("BackgroundColor") as Number);
        dc.clear();
    }

I have commented code inside function draw, so dc.clean can't be executed.

I see no difference for the watch face. Its look like screen (actually Dc) automatically perform clear() for each onUpdate.
Is it true? Why Background contains unnecessary dc.clear?