From my experience on the SE network so far, the intent of an SE network site is to provide a singular correct answer to each question. Basically, if someone has a question that's answered on an SE network, and they google it, they want the question to appear first so that person just needs to check the accepted answer for that question. This works fine for many of the SE sites: SO, SU, SF and many of the other sites get questions that have 1 answer that works for most people and maybe a few other answers that can be used if the popular vote answer does not work for whatever reason.
However, there are also a number of exchange sites that are based on an entirely different question logic:
- Worldbuilding has a focus on basically crowdsourcing answers to open-ended questions with no cut & dry answer. They are less "this is the right answer" and more "this & this & this are consequences of the statement from the question", where each consequence can be found in a different answer and accepting 1 answer usually is not really an option because it means choosing the most correct answer from several correct answers.
- Parenting allows people to get feedback on issues they encounter while parenting, which depending on the situation might not be the right answer to the next user to visit.
- Code Review is similar to Worldbuilding in that there are usually multiple correct answers, but each answer has their own merit and brings a different nitpick to the code provided in the question.
- Programming Puzzles & Code Golf is based on a competitive mentality where each answer is a separate contestant to the competition, complete with leaderboards, scoring rules and restrictions that can vary from "no loophole abuse" to "your code may not include the letter E". The main difference is that the "best" answer potentially can change days or even weeks later, when a new contestant tries their luck and beats the current leader.
There are other exchanges that have a similar issue: the basic way in which their field works and the tendency to have soft, open-ended questions where there can be more than 1 answer that's correct and most answers are equally correct. The SE paradigm started by the 3 original sites in this network where there is 1 acceptable, canonical answer and maybe a few backup methods just plain does not work for these exchanges, because they're based on an entirely different methodology.
I am NOT trying to say that these SE sites should be removed, closed or otherwise impeded though. These exchanges have their own right of existence, because they still have a purpose and a devoted audience. They also still have the main focus of the SE network in them: questions and answers, guided by a reputation and voting system to weed out the bad answers. However, they use their system in a different way: instead of "this answer/question has helped me, I shall upvote it", it's "this question/answer is intriguing and interesting to read, I shall upvote it". this is not a wrong way, it's just a different way. And they still help people: many of these SEs get traffic from outside the network from people trying to find answers to problems they have.
The main difference is that these softer SEs usually have a bigger focus on discussions instead of decisions. That is one of the places where the SE framework in my opinion starts to work AGAINST these softer exchanges: the SE framework focuses on getting a correct answer, with discussion being relegated to chatrooms with far fewer users, much downtime and a rep requirement. Moderators are encouraged to move discussions to these chat rooms, making it harder for people to remain interested in them because they can't consult the question that prompted the discussion as easily. Comment threads are moved to chatrooms, sometimes even before they're finished, often hiding astute remarks and observations that are part of these comments and can easily change the quality of the answer or question they're part of.
I think banning these SE sites is not really a good idea. They're popular, they're interesting and they fill a niche (for example: googling World building gives the SE site as the second page where users can place their own requests for comment, after Reddit which has an entirely different format). They need their own solution, but I'm not sure what that would be.