This question already has an answer here:
Many users decide to ask questions on SE sites when they are done spending time googling for the answer. That would explain why it's no rare to see question demonstrating tight deadlines or even desperation. Wouldn't it be great, specially on those cases, if we could know when someone is working on our questions? It's worth mentioning that some answers does take time to be written.
We can see how many people have seen our questions and the number of answers it's gotten, but we lack a mechanism saying: "2 users are elaborating answers to this question".
Another side effect of that would be users prioritizing questions that have no one working on them avoiding duplicate answers.
I hope I made myself clear.