How best is the Yahoo! Answers helping its benficiaries and to what extant?

In first place since so many people are spending their valuable or otherwise time here itself speaks about its success and usefulness. I agree that Yahoo Answer may not provide exact answer to one's problem but answerers here do give you a good idea about the query.

On other side it is really fun to reply queries of others as also to know that there are so many queries all over.

May be presently there is curiosity factor (it is only six month old - started on 07 Dec 2005) therefore lot of below average questions and answers are there but I hope it will be mature over period.

Lots of hits on Yahoo! = higher advertising revenues

Note how there are no ads in this, yet. They may be generating data to market to potential advertisers the benefit of advertising in Answers.