I naively presumed mods and meta mods would dampen the impact of voting rings and disagreement votes. One additional tool might be requiring a "reason" for the downvote as /. used (still does?) to do (off-topic, irrelevant, inflammatory, etc.) and for people whose downvotes massively stray from the reason, revoke downvoting privs.
You'll almost instantly get downvoted to at least -5, despite the verifiable truth of the statement.
It would make vote brigading really attractive as well. Imagine if /r/TheDonald users could have caused a financial impact to anyone just by downvoting their comments. Reddit would have been a nightmare.