jojatater,
Plan for the worst- practice for the best. The worst that can happen is to hit the shoulder joint with a broadhead.
I have blown completely through both shoulder blades with MY setup, but NEVER through a joint. I shoot considerably more weight than 33 lbs at my draw, and I shoot very heavy arrows.
Momentum - the resistance of an object to stopping, is greater, with more poundage and weight. Think of it this way- throw a brick and an angel food cake the same size at a snowbank. Which one will penetrate farther into the snow?
Errors are common with bowhunters just starting out- I've had guys who were experienced tell me they shot something "right behind the right shoulder, or the left shoulder" I can't tell you how many times, and they ended up having shot it in the butt, on the opposite side, as an example.
Things happen...plan for the worst, practice for the best.
A new hunter, with a 30 or 33 lb bow or whatever, if they make a mistake, might get soured on the sport if their first shot is a bad one. I would not want to take a chance were it my wife, that she would make a bad shot...because I know she would not handle that well.
Anyone can build muscle, technique, and increase their weight to a higher level. I think 33 lbs is too low a bow weight for the taking of game in a quick clean manner, because everything has to work PERFECTLY every time you shoot, or you end up in trouble.
You don't have to be involved in many late night, flashlight, hands and knees woods walking expeditions to get fed up with marginal hits and no deer at the other end of that trail to decide that you need to execute better to stop it from happening again....there's plenty of reasons to have a sleepless night...worrying over a deer you made a marginal shot on is not a reason you want your wife sitting up at night for.