Cyberbullying and Cyberstalking are Crimes. Why won't IMDB put a stop to it?

Cyberbullies may disclose victims' personal data (e.g. real name, home address, or workplace/schools) at websites or forums or may use impersonation, creating fake accounts, comments or sites posing as their target for the purpose of publishing material in their name that defames, discredits or ridicules them.

Cyberstalking is a form of cyberbullying. Cyberstalking may include false accusations, monitoring, making threats, identity theft, damage to data or equipment, the solicitation of minors for sex, or gathering information in order to harass. Such actions and harassment against a target by an adult constitutes cyberstalking. Cyberstalking often features linked patterns of online and offline behavior. 

Common tactics used by cyberstalkers are performed in public forums, social media or online information sites and are intended to threaten a victim's earnings, employment, reputation, or safety. Behaviors may include encouraging others to harass the victim and trying to affect a victim's online participation. Many cyberstalkers try to damage the reputation of their victim and turn other people against them.

There are consequences of law in offline stalking and online stalking, and cyber-stalkers can be put in jail. 

Stalking online has criminal consequences just as physical stalking. Cyberstalking is an extension of physical stalking. Among factors that motivate stalkers are: envy, pathological obsession (professional or sexual), unemployment or failure with own job or life; intention to intimidate and cause others to feel inferior; the stalker is delusional and believes he/she "knows" the target; the stalker wants to instill fear in a person to justify his/her status; and the erroneous belief they can get away with it (percieved anonymity). UK National Workplace Bullying Advice Line theorizes that bullies harass victims in order to make up for inadequacies in their own lives.

The US federal cyberstalking law is designed to prosecute people for using electronic means to repeatedly harass or threaten someone online. There are resources dedicated to assisting adult victims deal with cyberbullies legally and effectively. 

One of the steps recommended is to record everything and contact police.