New users sometimes genuinely don't know about the accept feature, and a "Hey did you know?" can be appropriate. There may be some users who forget to accept answers as well. When you come across a clear case where the user has said something like "Perfect, thanks! I'll accept this once the wait period's up" and not subsequently accepted, a reminder comment may also be appropriate.
The rest of the time you're telling someone who knows about it to accept answers they don't want to accept. There are plenty of valid reasons not to accept -- not yet having a solution despite having an upvoted answer is probably more common for people who ask difficult questions. Those with real, difficult problems shouldn't need to accept answers that aren't solutions.
- Reminders to accept can be useful. I recommend being overly polite and so on.
- Nagging about the accept rate isn't helpful, because you don't have the right context to know why their accept rate is low. If you do know the context, leave the first type of comment instead.
Personally I hate the fact that the accept rate is displayed. First, I reject the claim some have made here that having a low accept rate displayed is not a form of punishment and shaming. To quote a comment made on another answer:
Accept rate isn't to shame people, but to allow answerers to concentrate more time on those people who engage more in the site – Casebash May 10 '10 at 5:32
The purpose is irrelevant. What are the actual effects?
- Users make comments intended to shame those with low accept rates.
- Users make polite comments intended to gently remind a user to accept may still cause the user shame. You've probably noticed that people can get awkward when you tell them they've got food in their teeth or something. Now imagine that everyone in the room heard you tell them (equivalent of publicly posting a comment). It would be perfectly natural to be embarrassed in such a situation.
- Users who notice or are told that other users refuse to spend time on their questions due to the accept rate are likely to feel rejection and/or shame and/or any number of other negative emotions.
There may be the rare case where a user is genuinely glad to be reminded if they had intended to accept an answer and forgotten. In all other cases, the emotional effect is negative. (You may argue that this is desired, but I am not making any claim about that yet so it's irrelevant.)
Given this negative effect, let's enumerate what it causes in turn:
- It discourages people from asking about difficult problems that are less likely to be solved. Stack Exchange is about expertise. Expert questions should be encouraged.
- It punishes people who have in fact asked expert questions that haven't yet been adequately answered. Not only with feeling rejected or whatever, but in not getting further answers.
- As a result of the previous two, it pushes away experts who want to do more than answer, or want to participate in a site where they and other experts could do more than answer.
- It pushes away people who want to participate in a site where people are treated with respect indiscriminately.
- It aids and encourages rep whores. Yes, everyone is free to participate as they wish, including playing the rep game. But we should encourage excellent and constructive behavior, not just acceptable behavior. Encouraging people to give all the attention to the easy-rep questions doesn't make this the valuable site for real development issues that we want it to be.
- It pushes away new users who weren't aware of the feature until they received a nasty welcome.
- Users who see negative comments think they're acceptable.
Now yes, there are users who just come to leech solutions and don't care to accept answers that they should. Should they be punished for having a low accept rate? Some points:
- Their questions may still be useful to others if answered.
- It's easier to use a throwaway account each time than get engaged in the site; the punishment may be ineffective.
- Have you seen how many people continually post crap without learning their lesson, even if their questions go unanswered? Again, the punishment is ineffective.
- You'll always have people like me who will answer a decent question if they can regardless of who asked it, why they asked it, or whether they've accepted previous answers. The punishment is ineffective.
- If the punishment's ineffective, the only point in executing it is vindictiveness. I don't want to participate in a site that promotes vindictive behavior.
- How can it be valid to ignore questions but invalid to ignore answers (not accept them)? This behavior seems inherently hypocritical to me. We don't stamp "ignores questions from low accept rate users" on user cards, why should we be stamping "low accept rate" on user cards either? Questions require effort and have value too, not just answers. Ignoring a question due to an external factor harms the site.
Yes, we should always encourage people to leave polite and constructive comments. But no matter how we encourage good behavior or discourage bad behavior, these comments will always be made if the accept rate is displayed. When it comes to the accept rate, there's a simple and effective option to reduce abuse. Get rid of it. The downsides are prominent and the upside is questionable as to its existence and entirely dubious as to its morality. I certainly feel that the benefits of removing it greatly outweigh the benefits we purportedly get from it.