True, but you can say the same thing about "friction". I still don't see a reason to throw throw out the window, unless you can think up of adequate and convenient terms describing the three types of throw you just listed.
I think this is simply false. The reason...throw (or friction, if you don't like the prior term)! Unless you're playing with ideal balls with an absolute zero coefficient of friction between the ball surfaces, pocketing a ball with inside english should be fundamentally tougher (edit: in general).
Consider your post and my post. Yours seems to suggest that inside is more difficult due to throw. Mine says that the idea of "throw" is what has confused people to believe inside is tougher than outside. Seems to me that I"m talking about you. Is that possible? Or do you think I'm just a crackpot who thought on the same lines as you and now don't? Would you rather think they're the about the same difficulty like I do, or would you rather blame throw and continue treating inside as being worse. To me, I'd like to make inside seem equal and not have to say things like "inside is worse."
Fred