I agree Dave, but to quote your link: Pilots should fly precise routes as depicted in the chart - "corner cutting is to be avoided"
Just because an aircraft is capable of maintaining safe flight with a SE failure doesn't mean they can gash off the route and straight line it down the Thames!
ME RW can indeed travel where SE can't and be given clearances that would be inappropriate for SE but, when following a route, you are to follow that route - unless subsequent clearance or vectoring is given.