It could apply to anything, I've heard of vegans who go as far as not using anti-bacterial soap because they don't want to kill the bacteria, or not eating honey because they consider the honey as stolen property belonging to the bees.

My point is in order to do something you wouldn't like done to you to something else, not out of necessity, but just because you feel like doing it, you may have missed an update or two from evolution's package manager.

For a lot of people it applies to plants as well.

I wouldn't for the sake of it willfully maim or destroy a plant.

That said, I'm also not the kind of guy that watches his footsteps to avoid stepping on ants or grass.