I believe seeing your score go up serves as an incentive to write good posts, and conversely seeing it go down is a deterrence for many people.
On the other hand I think it also drives low quality circle jerking (parroting superficial stuff already said many times, so people updoot you for saying the thing they like seeing) and whatever the opposite is called, where people get downvoted for well written, informative posts that just aren't in line with the in-group opinion of the thread regulars.
For me the ratings also serve as feedback as to whether anyone cares about whatever contribution I made, or how popular or unpopular the position is, so I can gauge the general slant of a thread or the community in general.
I would expect the people who are obsessed with their forum-enemies and "team red vs team blue" type of thinking, the people who see ratings as a way to fight their culture wars, to manually check posts and continue as usual, so I wonder how effective it would be in curbing that.