What are some benifits of using a server based Mock service over a local mocking service?

For testing applications making HTTP calls, I am using Spring based mock server classes which locally match requests and respond with the specified data. I have been suggested to also test my calls through an online mock server (something like http://wiremock.org/).

(If any) What are some advantages that could be derived from such an online mock server over a local code based mock server?