Yes and no, maybe on /b/ but not really on the other boards.
For instance /v/ is mostly very sexist, /pol/ is mostly very antisemitic. Even when there's no voting/karma of any sort if an idea gets a lot of traction at some point people who disagree will get flamed and passed a certain point will give up/stop discussing the topic/leave the forum for some other place.
When someone posts a very unpopular opinion it can't be downvoted, of course, but it will either be ignored or flamed until the thread gets completely train-wrecked/expired/killed by the mods.
For instance /v/ is mostly very sexist, /pol/ is mostly very antisemitic. Even when there's no voting/karma of any sort if an idea gets a lot of traction at some point people who disagree will get flamed and passed a certain point will give up/stop discussing the topic/leave the forum for some other place.
When someone posts a very unpopular opinion it can't be downvoted, of course, but it will either be ignored or flamed until the thread gets completely train-wrecked/expired/killed by the mods.