PAPIs are there for people sitting in the cockpits of big things with spare engines. They are not there to permit elastic-powered puddle jumpers to be dragged in from 97,000 miles out, having called final just after re-entering the Solar System despite the 3 aircraft just about to call ready at the hold. Will the airfield management or, indeed, your mum be pleased with you if you collide with a gildeslope indicator in the undershoot after your engine quits, when you are there in your C150 perfectly on the slope intended for all those nice Airbuses?