Funny, the TrackPad I replaced in a friend's 2009 13 inch MacBook Pro was like 4 steps, if. Remove screws from bottom pan. Remove battery connector. Remove battery. Remove 4 screws holding Trackpad. Done.
It all changed around 2012.
My information came from the link I supplied: "The MacBook Pro 15" Retina Display Early 2013 packs the battery, keyboard, trackpad, and upper case into one assembly. If any of these components fail, the entire assembly must be replaced."
Your guide is for the 13" model. I do not know whether it works for the 15" model, but I can assure you that I am not intending to find out.
But yes, it can be done for one $80 in tools and materials at least on the 13" model, unfortunately in 47 (well 93) steps.