Users not accepting answers, is an issue that I believe Jeff and co. are attempting to address. However, I do not believe this makes it appropriate for people to encourage them in this manner. Things that may seems like gentle suggestions to an experience user can come off as pushy and/or condescending to a new user. The SO system has been designed and refined in many ways to encourage user's to accept answer; let the system handle it. If you find a comment (or question/answer) offensive, you are welcome and encouraged to flag it for a moderator. In time a moderator will see the notification and address the situation, if they feel it appropriate.
While I wouldn't expect any of these to happen in this case, others systems in place for dealing with inappropriate behavior include, if a user gets flagged too many times, they will be docked 100 points, warnings from Jeff and co., the penalty box and perhaps banishment if deemed necessary.
Additionally, in defense of the asker here (and note I suspect I wouldn't know a single answer on SF), only two answers to one of their three questions has any upvotes; so this person is certainly no where near the worst offender, if an offender at all of not accepting answers when they should.