This is called domain parking and it is actually a benefit.
“Domain parking is an advertising practice used primarily by domain name registrars and internet advertising publishers to monetize type-in traffic visiting an under-developed domain name. The domain name will usually resolve to a page containing relevant advertising listings and links. These links will be targeted to the predicted interests of the visitor and may change dynamically based on the results that visitors click on. Usually the domain owner is paid based on how many links have been visited (e.g. pay per click) and on how beneficial those visits have been. The keywords any given domain name provide clues as to the intent of the visitor before arriving. For example, the domain fast-weight-loss.com might point to a page of links to diets and weight-loss drugs.
Another use of domain parking is to be a placeholder of an existing web site. A company might choose to use this method to redirect its website traffic to another web site it owns.” -Wikipedia
It is usually created by large companies that get a lot of traffic and customers. This costs hardly any money if your host allows you to have parked domains. All you pay extra is domain names.
The purpose of parked domains is to get more traffic towards your site. If you have a company that is called “designxpress.com”, you might also park the domain “designexpress.com”, just in case customers do a typo.