Some questions are easy to formulate and can stand as they are.
Some are complicated. They tend to attract a mix of comments asking for clarification together with hasty answers that haven't been thought through or simply make assumptions.
Instead of the complications of using a sandbox or getting put on hold by vote or by moderator, I suggest the following:
A. Automatically put every question on hold for 24 hours. This allows comments asking for clarification but stops ill-thought-out answers.
I don't believe that anyone's question on this site is so urgent that it can't wait for 24 hours.
B. Allow the user to put their own question on hold immediately. I would certainly use this facility. It would allow me to carefully consider others' comments and edit the question accordingly. It would prevent me having to deal with premature answers.
The problem with the sandbox
Some people say that the sandbox avoids clogging up the main site. I don't believe this is true.
(1) Many questions are put on hold by the community without being tested in the sandbox. These already clog up the main site.
(2) I'm not convinced that this 'clogging up' is actually a problem. We're living with it already.
(3) A lot of people don't spend time looking at the sandbox in order to help others. I personally never do. I believe it is inefficient and doesn't guarantee that a question will succeed on the main site.
Is there any technical reason that would prevent my suggestions A and/or B from being implemented?
Is there any logical flaw in my proposal?