I'm feeling like the initial analogy fit the premise better.
It feels a lot like spillage to me, antenna or not, but I admit my emf is weak
The antenna array is actually distorting the electromagnetic field and whatever is plugged to it is actively draining power from the power line. If there's no antenna the power line lose no energy through the field[1], it's not as if you were collecting lost power.
[1] in fact, you can even say that the energy is not carried in the cables themselves but in the air surrounding the cables!
From a physics perspective It's not the same thing at all: with the water sprinkler, the water is lost no matter what for your neighbors. But with the electric field, there's no power loss unless you tap into it.
To get back to your water sprinkler example, it's as if your neighbors' hosepipe got trough your garden to get to his sprinkler: you can argue that this is a environmental disturbance to your garden, but that doesn't allow you to take water from the hosepipe for your own use.