I posted this response in Philipp's forum:

I am a member of several open-source software projects that use wikis as tools for open collaboration. The spam in our wikis hurts our development efforts in several ways.

First, it spams the RecentChanges pages, making it less useful as a change notification system. In many cases, this also spams the mailboxes and newsreaders of users who subscribe to RecentChanges notifications. We are no longer able to use the wiki as a communications tool because most of the messages are generated by SEO spam.

Second, it puts off-topic words and phrases into our wikis. This causes them to show up in completely unrelated web searches. Strangers then find our wikis thinking that they are related to other topics, and edit pages without realizing what the site's actual purpose is.

Third, in order to fight these effects, we now need to spend ridiculous amounts of time blocking or cleaning up after SEO spam.

Please, don't spam wikis. The SandBox page is there for a purpose: to allow users of the wiki to learn to use the software. It is not meant to be "a place where anyone can create backlinks."