That would just fracture the voting (which already needs more scale to be useful at all), and the people who wanted to abuse it would not use the alternative option.
What's really needed is the ability to view a grid based on the subjects you are interested in, for example to be able to remove "politics" or "word games" from your view so that you don't systemically vote them all down.
Separating questions from discussions is also a good idea. In any case, those things conflict with the ease of the "all in one" view and people will be sure to hate the change but it would be a big improvement.
Another thing that can be improved is that the negative ratings offer more incentive than the positive ratings, because the negative ratings help hide information and the positive ratings don't provide the individual user with an immediate benefit. So doing something like making replying auto vote up the post/thread being replied to would make the use of the behavior more positive. After all, you the voting ideally represents posts/topics worth reading and replying to.
Note: before anyone asked why that's different from reply count note the difference between unique users and total replies. A thread with 1000 respondents and 2000 posts may be more worthwhile to read than a thread with 2 respondents and 20,000 posts.
Some tweaks need to be made here, the system is not ideally suited for positive uses and those two changes would make a big difference.