I disagree. Each nipple has a small ball sitting on machined seat, as long as there is no sediment holding the ball open higher pressures make the ball seat better.
Pray tell how?
Obviously if they are leaking due to to sediment on the seat then higher pressures will make them leak larger quantities of water.
Exactly correct.
Manufacturer's instructions for introducing chicks is to turn down the water pressure extremely low, less than an inch of water height,
Well only one of the big four, Ziggity, recommend less than 2". I Quote Ziggity-
How do you determine the best pressure setting for the watering system?
Virtually all manufacturers of nipple-type drinkers without catch cups recommend minimum pressure settings for day-old chicks. Most manufacturers recommend settings below 10 cm to start, while Ziggity Systems recommends only 2.5 to 5 cm (1 to 2 inches) of column height pressure in order to ensure dry litter from the very start. After the first week, manufacturers differ on pressure settings, but generally pressure settings do not go beyond 50 cm (20 inches) of column height.
To determine the correct pressure setting, examine litter conditions. If the litter is wet, reduce pressure until it starts to dry. Only then, increase pressure. Producers should strive for dry, friable litter.
The other three biggies - Chore-Time, Val and Impex all recommend 2 to 4 inches first week of life. To keep the litter dry.
so that the nipples drip a little to attract the chicks to the nipples.
Not the case. They used to recommend "brooming" the nipples to have a drop of water appear but not even that anymore. Brooming was walking the drinker line with a soft broom contacting the nipples so the last slight action of a bristle left a droplet without it falling off the trigger pin.
Higher pressures help seat the ball.
Only if the weight of the water can compress the solid stainless steel. That cannot happen, not even at the bottom of the Marianas Trench.
Our commercial water lines have a a regulator bypass so that you can apply full supply pressure to the water lines to blast out any debris. When I flush the lines at high pressure, I do not see any leaking nipples.
Of course not. They do not leak under low pressure either.
In fact trying to operate them by hand takes a good amount of force to operate the nipple.
How much more force? Are you saying that it takes more force to lift a measure of mass in the bottom of a pool than it does near the top of the pool? Are you saying tat a rock is less buoyant in shallow water than it is in deep water.
Birds that do manage to peck hard enough to operate the nipples at this time are usually met with a spray of water from the nipple due to the high pressure.
More water coming out due to the pressure, yes. The nipple being harder for the bird to operate due to pressure, no.