Tap water is often hard so pouring it on the plant leaves deposits behind.

Another justification is that when it's sunny water droplets on leaves act as lenses and might burn the leaves.

It is also known that wet leaves increase the chance of fungi, mildew, etc. taking hold on them. The article shows that plants are also well aware of that!

I was always told that the leaves just don’t need it and it gets in the way.

I wonder would pouring water onto the leaves of chilis plants encourage it to produce hotter peppers?

The substance that makes chilis spicy is a natural anti fungal.

I have a chili plant at home with 4-5 baby chilies growing. Once those have ripened, I'm going to do this experiment.

Plants do most of their water absorption through their roots, not their leaves. They're also prone to fungal problems when their leaves stay damp. There's no reason to water the leaves rather than the dirt around the roots, unless you're applying a foliar spray or watering something like a tillandsia that doesn't normally live on the ground.

The article says it's no surprise plants panic because water spreads disease, which is exactly what we're avoiding by not watering the leaves. It's not to save our plants' feelings, although the root cause of the feelings and the problem we're avoiding might be the same.