Many, many, many years ago we experimented with a reputation/post feedback system similar to the request in this thread. The intent was to have the equivalent of both like (+) to encourage quality posts and dislike (-) to discourage low quality posts. However, the negative caused issues. A simple dislike button that shows who disliked the post creates animosity between members, whereas someone posting "better information" in reply keeps the focus on the information being presented. If the dislike button is anonymous, it prevents tiffs from forming between members, but then it can be worse, giving someone a bad feeling if they take the time to share their technical experience and get a downvote from a member who might not understand the post. Somehow getting a dislike after taking your time to try and help creates a real sinking feeling. So while it can be useful overall, it creates specific problems. We tried to solve this by using weighting based on the feedback a person's posts have received (e.g. only allowing someone to dislike if their own posts were strongly liked and even weighting the dislike based on someone's own like score, so that new members who don't understand something don't cause a major impact but dislikes from someone who is well regarded based on the quality of their own posts has more impact on others when they click a dislike button) but then this can also create a feeling of inequity that also causes issues. We tried adjusting the weighting to take into account
likes/dislikes received, post count, and membership duration to try prevent random or inappropriate dislikes, but having a dislike was itself a very disliked feature overall at that time.
Maybe a future experiment would be to allow someone to set their own viewing threshold, and then have the dislike only control that visibilty, so someone could choose to view everything, or hide all post that had 1, 5, or 10 dislikes for example. But then that creates an issue with context, whether to show replies to hidden posts or on the flip side whether quality posts get hidden because they are in reply to a hidden post, whether a thread would make sense with or without a low quality post that itself wasn't great but caused the thread to take a new direction for example.
The like button isn't perfect as you may get someone liking a post that doesn't merit a "like" because they simply want to thank the person for replying, but overall implementing a dislike button without creating problems by doing so is difficult.
We'll see what the future holds, but for now, you can manually ignore anyone who you feel never posts things that you want to read. Click on a username and click Ignore.
And for anyone reading this, if you use the like button, please use it to encourage high quality posts and posters that really answer a technical question well. Many thanks!