Learning and having an open mind are not bad things ... this is how one non expert person sees it, be nice to people and don't fight.
I'm legitimately trying to help you understand the flaws in your thinking. I don't have ill intent or want to make this a heated argument, but, as you said, a learning experience. ZeeOSix may have been a little on the flippant side, but reading up on fluid dynamics would have answered your questions and help you see the flaws in your thinking. One major principle of fluid dynamics is fluids push in all directions equally (paraphrased). Similarly, fluids move through openings with equal pressure across the entirety of the opening.
A thumb over a garden hose, or a nozzle on a fire hose, nozzle on a faucet, etc. are perfect examples where changing the exit shape/size did not change the fact that all fluid leaving the hose is leaving at the same velocity with the given shape. On an open hose, all of the water leaves at the same velocity and pressure across the entire hose opening. Put a thumb over the hose, all of the water still leaves at the same velocity across the entire opening despite the velocity being higher than an open hose. Observing an open hose velocity to a partially closed hose velocity and then applying the two different observations to a third opening with a small and wide side is an incorrect comparison. They are separate systems that cannot be compared in this manner.
Another way to think of this, if the garden hose had a triangular opening instead of a circle,
but kept the same surface area as the circle, the water would exit at the same velocity. The corners do not get an increase in velocity relative to the center simply because they are tighter spaces.
Counter argument using your methodology. A thumb over a hose does not make the hose exit a perfect circle, but instead something like a half moon. The velocity/pressure at the corners of this half moon should be higher than the center of the half moon where there is more area, but truth is the velocity is the same on the entire opening.