My understanding is that the editmyusercss and editmyuserjs user rights were introduced due to security concerns. They were and are a necessary evil, as their existence stands in opposition to MediaWiki's principle of openness. This principle is inherited from broader wiki culture.

I'm doubtful that a new editmyuserpage user right would be appropriately aligned with MediaWiki's values.

I tried to expand the task description, but there nuances that I'm not sure I captured.

I described the issue with very new users not being able to edit their own user pages. In addition to this complexity, there's also the matter of configuring MediaWiki to automatically semiprotect all pages in the User namespace that are not subpages, I think.

MZMcBride, the RfC specifically included a provision for very new users to be able to edit their own user pages. This was noted by the closer on the talk page. The task to enable that to happen was split off into a separate task, T149484 (not my doing or idea).

In T149484#2754254, @Funcrunch wrote:

The task to enable that to happen was split off into a separate task, T149484 (not my doing or idea).

It's mine, for a separation of concerns:

• T149484: development — new MediaWiki core feature — applies to the MediaWiki software
• T149445: configuration — enable the feature on en.wikipedia — applies only for Wikimedia wikis

There are particular tasks used as tracker, roadmap, goal, etc. but for concrete actions, the more efficient way for tracking is one idea, one thing to do = one task.