Ahh sweet, sweet oblivion.
They do it because there is no penalty and almost no risk of getting caught at the moment.

My opinion, you're spot on. All of you even the guy warning about retaliation.

Mod wars are perfectly natural in a system like this.
Some jack ass down modding you for no reason deserves to be called out and back modded into oblivion. Not just by you, but by all the people that have to dig through and find your content because of said jerk,

What stopped nuclear war from ever becoming an issue was the concept of MAD or Mutually Assured Destruction.
If someone can downvote, then there must be a way the system is recording it. If there is a record then there is a way to find said jack ass and nuke him.

The best solution would be the formation of a vigilante pool for hire. Including creation of a tool, being either a site or browser plugin to report false down mods, uncover who did it and downvote their most lucrative works that day into a crater.