are you sure you haven't been watching too much of this :p
https://www.youtube.com/watch?v=DTQXYeTV7a8
this is a circular argument as if you don't move the feet there is nothing that you can do with your hips that will prevent you being dumped on the floor.
sound advice and the closer the range the less time there is to react to the takedown (as in the single and double legs evidenced in the clip) attempt however with contact the change of level can be felt whereas from out of contact (even if within range) the level change has to be observed. Of course in contact range there are a whole other array of throws, trips etc available to a grappler that are not available at range which do indeed increase the liklihood of ending up on the floor. FWIW my comments are based on my own experiences not on what someone has told me so maybe my opinions will change over time.
With regards to Jose Aldo all of the factors that you mention of course come into play however watch his recent fights and listen to the commentary. The comment I made was taken from a commentator who has fought and coached at the top of MMA, of course he is probably wrong and you are right. Maybe you should think about calling the UFC and asking for a slot on the payroll. ;)
Its friday afternoon and I can't take this discusion too seriously