Allow me to accept an answer immediately
I asked a basic question, and got a right answer in 1 minute. Why can't I accept it?
If I don't accept the question that is a problem: lower accept rate. If I would accept it, I have to wait 10 minutes unnecessarily. If I come back later then I may forget to accept it.
Let's create an abstract case:
There is a very basic question:
The answer comes from A immediately:
The questioner accepts the answer in (1 minute!), because he/she checked it and that was correct.
A can continue its work unless clicking on accept answer icon in every 30 sec.
B, who are browsing the questions list, will see, that 1+1 is already answered and accepted, and won't start answering the question. He/she may don't even open the question, because it is solved. B see this:
Here is the feature request:
C, who is still answering the question first got a message, new answer posted. 1 minute later gets a new notification, the answer was solved, here is the solution: 2. C will not thinking about what can 1+1 be, but will chose another question to answer. And C won't post the right answer as a duplication.
Let me present the case if the answer is not correct:
the answer comes from A immediately:
The questioner accepts the answer in (1 minutes!), because he/she checked it wrong but figured out that is correct. A is happy that he found an answer so fast.
B, who are browsing the questions list, will see, that 1+1 is already answered and accepted, and won't start answering the question. He/she may don't even open the question, because it is solved. B don't know that the solution was false. B will still ignore the question though may know the right answer.
C, who is answering the question, will see that the solution is wrong. He will post the answer: 2.
A is working, because he thought that the answer is 3. One month later he will return back to Stack Overflow because this error caused a fatal error. After hours of debugging/or seeing C's answer found that 1 + 1 = 2. He will remember it forever.