Maybe they include things like stashing/popping current uncomitted changes, switching to target branch, pulling source and target branches first, rebasing feature branch onto latest target branch, resolving conflicts, ... ? All of these are things I has to do at one point or another to 'just' merge some feature branch from somebody else into master while I was working on another branch myself. So if they combine all of that in one command including taking care of everything which can go wrong I can imagine getting 15 commands.