Although WHOIS provides information that can be very valuable, there are people out there who choose to abuse this information.
While the original purpose of the WHOIS database was to provide a directory for domain owners, the publicly available information opened the doors to mass spam and other abuses. WHOIS tried several things to prevent this from happening, including changing the terms and conditions of WHOIS databases to include a statement that the information revealed should not be used for such purposes. This change has proven to be mostly ineffective. To further discourage data hackers, most WHOIS sites have implemented a script with a random graphic display of numbers or letters. When a person requests information from a WHOIS website, they will be asked to manually type a series of letters or numbers. This way, "Bots" or data scouring programs cannot read the graphic displays and are unable to manually enter them. This disables results from automated queries.
This has slowed down many hackers, but beyond precautions such as these, there is no real mechanism in place to catch, identify, or punish abusers of WHOIS information.