Most people have friends, parents, parents' friends or friends' parents who have gotten divorced. Just because it is common, doesn't mean that everyone is intimately familiar with every part of the divorce process. That lack of understanding often extends to the concept of modifications.
Victims of domestic violence find themselves in a difficult position when they want to get out of their relationships. If they're married, they may wish to ask for a divorce, but doing so could put them in danger. Likewise, leaving could result in the abuser seeking them or family members out, threatening their lives.