I tried to create Map extensions with a comparison table about the software found in Category:Map extensions but I just get MediaWiki:Abusefilter-warning-wrongwiki, which currently says:
 | This site is for documenting the MediaWiki software. It is not the wiki that you set up for your class, workplace, or personal use, nor is it Wikipedia. Think this is an error? Ask at Project:Village pump. |  |
While I find the grumpy cat amusing, it's also quite unwelcoming.
Creating pages in the main space is limited for new users. Try creating it as a subpage of your user page and then moving it. Also, note that there's already a redirect page "Maps extension" so creating "Map extensions" might not be the best name---something like "Map extensions comparison" or "Comparison of map extensions" might be better.
I don't think their issue was with the validity of the message, but with its presentation/tone instead. Which I definitely can agree with — there's no need for the message to be so condescending and, well, grumpy.
Thanks :) Maybe the error message should say something like: Hey, editing the main namespace is limited for new users. And maybe don't show a grumpy cat to new users trying to improve the wiki.
I've updated MediaWiki:Abusefilter-warning-wrongwiki with those good suggestions.