Why answers.yahoo.com failed? ?

A sad story 

.2021-04-07T13:58:17Z

Lack of proper maintenance
Lack of proper moderation/oversight
Influx of users who abused the site and didn't care
Advertisers choosing not to post their ads on a site full of garbage content

Anonymous2021-04-07T09:41:38Z

Because Yahoo! is censoring people based upon their politics.  I know it's the "thing to do" these days, but not if you want to survive in the long run.