They said its nofollow but I get backlinks from them. give it a try, good answers and it may help ur traffic as well
Your answer must be really quality and high vote so your answer able to rank on top . Just like search engine which you wish to show on top of ranking. Same to answer which high vote answer only able to show on top. Reply with professional answer and get high vote of it so people can see what you share with .
Yeah, that doesn't really make any sense seeing as questions expire and they have to choose a best answer.
if you've written a good content (question or answer) with the link of your site in it. I think yahoo answers does really create traffic.