Just because I may disagree with some snooker ideas doesn't mean I disagree with everything. Stance is personal. The 'squared off' stance may or may not work for most poolplayers. As long as you're not stressing your body, can swing the cue from just the elbow, have a smooth transition from backwards to forwards, and have a natural finish for your tip, that is a measurable distance past the CB, whatever somebody does is fine. The questions concern accuracy and repeatability. The elbow is a hinge that can only open and close in a dead straight line. The shoulder is a ball & socket, making it a 'universal' joint...meaning it can easily steer the cue. Therefore, if your cuestick is moving in towards, or away from your body, as you backswing or forward stroke, it means you're swinging from the shoulder...not just the elbow. Hence the higher probability of small stroke errors, which are compounded by too much grip pressure. When you swing from just the elbow, the range of motion is static, and the only variable that can screw up the shot, is the wrist...which, like the shoulder, is a universal joint. This is why you want your wrist to hang straight down, when the tip is at the CB. Lots of players cock the wrist here, and it leads to a poor transition for most of them, especially when trying for a power stroke.
As noted by others, engaging the shoulder as part of the backswing and/or the forward accelerated stroke is likely dangerous, and produces more stroke errors, than a pendulum stroke, which does not engage the shoulder. It is simply not true that you cannot generate sufficient speed using a pendulum stroke. Many pros don't know what they're talking about when it comes to pool physics...that's a fact! It is fairly easy to produce 22-24 mph break speeds, using nothing more than the weight of the cue, and a perfectly timed throwing motion (and a relaxed grip on the cue).
The point I continue to stress in what I teach, is that the more relaxed and balanced you are, the easier it is to accurately set up and deliver the cuestick..and consequently the easier it becomes to learn to 'feel' the cue, and learn speed and timing. The more tension you insert into any part of your pool game, imo, will likely contribute to more misses and missed position. Professional players, be they pool or snooker, etc. are unique in their individuality. They have learned to do their "thing", their way, perfectly, every time, through years of dedicated shoting. The huge majority of us will never begin to reach that comfort level with our stroke and timing...but it can be taught, and it can be learned by anyone who has the patience to practice good fundamentals. The quick way to that is to get some quality instruction from an instructor who does video analysis.
Scott Lee
http://poolknowledge.com
Scott disagrees with most of what Joe and almost all the snooker coaches teach, especially regarding using the body as a guide.
Although it is important to note that Joe had bad vision in his right eye, and as such he was able to bring in the cue closer to his body than some modern snooker players, which you can note by where his cue ran(it touched under his tie), he also advocated much more of a boxer style stance that what is commonly employed by snooker players these days.
Check out some videos of him on youtube, and compare his style with that of a snooker player, make your own conclusion.