Lol, most of the time people can make up for the fact that clicking is less efficient by taxing themselves far more than someone using keybinds, this doesnt mean its a good idea though
In swtor you can get away with a lot of clicking, because the pace is fairly slow. Jump into a game where things happen at a lightning pace, and the clickers will just get mauled. Not only from being slower on the draw, but because a portion of their attention is elsewhere.