Yes time can be spent better some where else, but what about the current links he have. Some people who are doing link building they don't judge whether the link to their site will follow or no-follow they just do it.
Google will not spider your site because of the nofollow tag and they will not pass on any PR so for google it is no good however unlike what many people are saying here even nofollow links are important Yahoo has said that they will spider even no follow links that they find they will not pass on any juice but lets take this for example if you have a new site no search engines know about it and you post comments for example on a few sites that have Nofollow in there comments and post on yahoo answers which is no follow you will see that yahoo will spider you but you still need quality links that dofollow with your anchor text and some sort of content to rank in the search engines so it is good to get you called by yahoo not google and as far as MSN I am not sure how they treat nofollow tags yet
Yes, it is nofollow. However, yahoo answer provide a targeted traffic if you answer on the right question
We get a lot of backlinks from Yahoo Answer by providing related answers. Even though they are nofollow we have been seeing a lot of traffic being driven through from it, including one sale. SEO is only part of the puzzle, conversion is also important.
Yahoo Answers has no value in an SEO environment. It is another great example of how Yahoo take a great idea and screws it up. Don't waste you time with it.
If you're looking for links that helps your site PR, yahoo answer might not be that good. You should concentrate on searching sites that give you PR credits. For example, directories and blogs with dofollows.