Thoughts on Web Applications More & More Not Having Main Menus

Thoughts on recent trends of web applications not having a main menu across the top of the application?

Main Menu as in a more traditional horizontal menu across the top of the application. File Edit View Help

Should they be there, or get rid of them? If your target audience is still desktop and not mobile.

What trends or UX methods are pushing the removal of main menus in web applications other than mobile?