I was just about to ask the same thing about this post.
JD forum post FYI, on a phone the bar is below each post. I think when the switch was made I was starting a few more threads than normal and I now remember the option. I thought it was called “polling” though.
That gets a little confusing because Question/Answer threads have polling and voting has polling, and they aren't the same thing. If someone sets up a poll, it's usually clear, you vote on the question and move on. With Question/Answer threads, the Question is asked by the OP, people answer it, and the answer that is the solution for the OP, he or she tags as "the solution" by checking a box. The polling comes in there because every post trying to answer the OPs question can be voted on by everyone else. That polling can be used by someone else reading the thread to see if what the OP thought was the best answer actually is, or if the community's voting of the answers points to a different answer.
For example, if someone posts a question "My tractor suddenly won't start, what should I look at first". One person comes back and says "check your valve clearance". The OP says "Great, thanks" and clicks that as the solution, then runs out and pulls his valve cover off. In the meantime, someone else sees the thread and says "Always check your tune up parts first, check if you have spark". Someone pipes in with a post saying to "check if there is fuel flow". Others can then vote those responses as the real correct response (depending on what's worked for them), and probably no one will vote for the selected solution as a starting point. Op comes back into the thread after adjusting the valves likely didn't fix it, tries the other solutions and may change his selection of the solution. More importantly, folks wandering into the site later after asking that question of the search engines, is going to see the weighted responses and probably not get his hands quite so dirty as the first guy, because the community up voted the second reply higher.
This kind of thing may be too new of a concept for YT, but it does weight and organize replies based on the votes of several knowledgeable people rather than one answer. Whether people will use it or not sort of depends. It's not the default right now, so most questions will just be regular old discussions. But if the community likes the concept, we can make it so posts in the Manufacturer forum will default to the Question/Answer type thread and you'll see a lot of them. New people coming in will be more familiar with the Question / Answer type of forum and may occasionally pick to start the thread that way.
This has become very common in highly technical forums because people have bad, mediocre, and good answers, and the concept separates the wheat from the chaff. Some technical questions don't lend themselves to this though. Some are better served by Discussions, which is how YT has always been and will remain for now. It's up to the community whether this fits well and if so, it can be made the default for tech questions. One problem that could arise is if people just upvote their friends answers rather than someones answer who they don't like, in other words, ignoring the facts and voting on personality.
Try it on test forum and see what you think. When you select to post a new topic, stop and look at the tabs at the top, you can pick Discussion (the default), a Poll topic, or a Question. Or you can play with the one Brown David and I were playing with.