When rendering the diagram control along with some content/other controls in the web page, if page content exceeds the browser height, scrollbar will occur. So, when scroll/pan the diagram through touch, it breaks the browser default scrolling. So we have to provide a option to scroll/pan the diagram with two fingers like google map.
Meanwhile, for diagram builder like application, existing behavior should work.(simple touch to pan the diagram).
So we have to provide both the option and it will be decided at customer end.