When I make them I never use piping gel. It just make them shiney....not really necessary.
Now I haven't seen the tutorial you mention so I'm not sure. Don't they coat waferpaper b'flies w/it then sprinkle sugar on?
Well, just dust them w/sparkle dust or leave them plain.
In the tutorial, you use markers to draw the butterfly on wafer paper or vellum. Then you spread piping gel over that and sprinkle sugar over it. So I think the gel is what makes it hold its shape. They always look so thick and unrealistic when I do them out of mmf, so I wanted to try something new.