Several accounts using this service just for backlinks to personal sites, very similar each other, has been blocked, for violation of terms of use.

Please use this service properly. We discourage - and will remove soon - Walls with only links to personal Websites. 

We remind the Terms of Use of this service:

10. Use policy and account termination

You must use this service to publish your social addresses in your personal wall. Limited use of links (maximum 3) to personal websites is allowed; but we expect that you also publish links to your social networks' pages. Failure to do this in a reasonable time will lead to account termination.