In reply to Andrew Starr.

But in this case, if I switch theme, but miss the point that onboarding process for this theme was implemented by some plugin, I’ll get useless plugin activated. If it became common practice, after testing 3-4 themes, before choosing the one I need, I’ll get 2-3 plugins, which do nothing in my current setup, but could conflict each other in theory. I just mean that maybe in this case following exact guidelines, about moving such functionality into a plugin, a bit lost sense from end user point of view (but in theory exactly end user should be in priority, when we making any decisions how to do or not to do something)

But also I agree that complete onboarding process for WordPress should be much wider than just setting up the theme. And ideally it should be presented as some API/framework in the core. But until we do not have it, maybe it make sense to approve such experiments on theme level, after more detailed review?