I don't think every abuser is a conscious abuser.
It's still abuse nonetheless and a victim is still a victim, even if the abuser doesn't know he's abusing them.
I think there's a difference between people who get pleasure from causing other people pain or suffering, and people with their own (childhood) trauma who are using abusive strategies to preserve their fragile self images from eroding even further.
I think a small minority of people fall into the first category. Most of us don't like to cause people pain and suffering. We don't enjoy seeing others in pain. We feel guilty when we know we've done something wrong and hurt someone.
But I think most of people could or will at some point fall into the second category. We all have our own trauma, and we all have our ways of dealing with that trauma. And in order to protect ourselves, we all sometimes (unintentionally) hurt others. The goal here is not to hurt them. The goal is to avoid getting hurt ourselves. So we lash out, we criticize, we control, we get defensive, we shut down, we disregard the needs of others, we invalidate their feelings, we gaslight, we lie, we get jealous, ...
Most people do or have done this at some point in our lives. We may not feel like an abuser per se, but that doesn't mean people haven't experienced this as abusive. And they would be justified to feel that way.
Most problems arise when people are systematically using these strategies and feeling justified to do so because their trauma response has been triggered. When you ask anyone whether any of these abusive strategies is acceptable, most people would say no. However, providing the right context and the right threat to their self esteem (a percieved attack), people might suddenly say they have every right to react.
This makes abuse a grey matter (when actually it's not). As long as people keep thinking that certain situations justify abusive responses, people are going to deny being abusive when they clearly are. And those people aren't going to feel remorse.