publicly harassing “strangers” anonymously online

What are the main purposes for posting these messages? Seem like all the posts about this 30/31 years old girl are:

• Spreading rumours.
• Making defamatory comments about the victim online
• Impersonating the victim online by sending an inflammatory, controversial or enticing message which causes others to respond negatively to the victim.
• Harassing the victim in different social media.
• Leaving abusive messages online, including social media sites.
• Creating online content that depicts the victim in negative ways.

What is your motivation and intention to threaten or to stalk this person?