Board Thread:Wiki General Discussion/@comment-5645428-20160726135004/@comment-5645428-20160802085658

"But, a testing space for a proposed article layout restructure, yes, [this example] would necessitate a separate page where no other pages on the wiki qualify to serve the purpose."

Purpose. There needs to be a proper reason that you would need a user page extension, and in most instances this would relate to assisting with wiki development. For personal content, your profile is there for it.