I suspect a question is closed when it has already been sufficiently answered . Keeping it open means it would keep being 'bumped' and become redundant. If you look at Quora, often a popular question will have 4 good answers and dozens of low-quality ones. better to just close the question then.

Then I wonder if Stack Overflow should add a reason for closing, "sufficiently answered," so that the editor can choose that instead of the inaccurate and incendiary "no longer relevant."

There can always be a better answer.