User blog comment:Kirkburn/Technical Update: July 25, 2016/@comment-24014422-20160728191617/@comment-24473195-20160729153827

>  it is something we've discussed before, but the benefits have never really felt like they strongly outweigh the disadvantages.

I have to agree here, regular users can and do revert vandalism from other users. If a page is only editable by its "owners", then people can vandalise dead or inactive wikis for days or weeks before an admin / moderator / staff or VSTF cleans up the mess.

Personally, I'd suggest reducing the attack vector, and instead investing on the one TRUE global user page. One global profile page, and one talk page for each user. This technology partly exists in an extension called the Extension:Globaluserpage that automatically imports a page from a central location. The drawback is that it doesn't really propagate the edits back to the source, so it is a bit like  Help:Shared Help pages.

Also, @Luma.dash, users don't really own the user pages with their nicks. You can think of them as stewards of it. User pages are a resource to help build wiki. In fact, on wikipedia, someone can request a rename to "steal" another user's nickname, and inherit it. So long as the user is either inactive, or has close to 0 edits.