The page describing "What is Meta?" has a general description of what the intended purpose of the Meta site should be and outlines basic use cases.
The issue has been raised raised via this topic and others that perhaps common use and acceptance of various types of topics in Meta has transcended and moved beyond the description. I'm not making a value judgment on that case one way or the other. The basic premise here is one of - should the description for Meta be consistent with what is acceptable by the community?
Just a couple of pro-reasons:
As a new user, one may be more inclined to check the description of Meta via the Help page and thus, the page should reflect the most accurate description.
In the linked topic, rather than citing the Meta description, many users cited precedent and previous posts, despite those previous activities seeming to contradict certain aspects of the Meta description. New users should not be expected to immediately familiarize themselves with all forms of precedent and "general acceptance" - these things should be largely outlined in the help documents rather than nebulously defined by group opinion and precedent (although, it is fine for group opinion and precedent to shape the help document)