I don't know if people generally look for targets or culprits. Sure, some people like to blame others for everything and many people project their own issues onto others. This is a sub-set of our society that does this. Like an abuser may say that their victim is the abuser, when it's the other way around. I don't know if people who use the word toxic are necessarily doing this to look for culprits or targets. Bullies and abusers deliberately target certain people, yes. But I have found in my travels in life that toxic is generally used to describe something that is unhealthy.

Generally speaking, and in my experience there are indeed people who create unhealthy relationship dynamics - people who themselves are not healthy-minded or healthy emotionally. This does create what is often referred to as a toxic relationship. To me, toxic simply means unhealthy, and there are certainly many emotionally and mentally unhealthy people in the world.