Is that really true though?!?! Forget the Webber incidents etc for a moment. Just generally...
Historically they gave each other room. Then with increases in safety and tracks with run off emerging as the norm you started to see guys more commonly being forced wide. Typically you used the exit and compromised their run in the corner...but I am not sure I accept the "you run them out of room/track theory. God knows its dangerous making blanket statements as moves around the outside are common in flip-flop/S-bends etc.
But I do agree that the guy on the inside has the line and advantage and has the right to hang around , but if he is a wheel behind on a compromised line for the exit as he is entering so shallow then I am not sure its so clear cut.
So jumping back to the Webber theory I just dont think its so clear cut. If you try an outside move on a 90deg corner you have to expect you are going to be pinched on the exit these days and probably forced to take to the run off area as they take the line on exit if you are anything remotely wheel to wheel. This is where you are better trying to compromise their entry then get a better exit with the over-under style move.
But on a flip flop/S-bend the guy on the inside has to get back to the other side of the track asap to get a good run on the exit of the second bend. In the case of Webber-Massa, Masa forced Webber off the track after a dive bombing wheel clash when hsi normal line would have been to hand left on exit so he had a more optimum line for the second half of the corner. So you are free to tae the normal line but I guess to e its blurred with racing craft when you hang around the outside hoping to gain track position and the inside line for the second corner or final 90deg part of the croner