As a lawyer with many colleagues practicing family law, I don't think this is terribly fair. Divorces are acrimonious because the overwhelming majority of divorcees have fundamental issues with their spouse that they can't even verbalize, let alone work out. The underlying feelings that trigger the explosive fights about nothing (think toilet seats or dishes in the sink) are only magnified when blame for failure of the marriage and the dividing of assets/children comes into play. In other words: divorce is acrimonious because people going through divorce literally go crazy.
I would bet Wevorce is successful because it integrates counseling/communication into the divorce process, something that is basically prohibited when both sides are represented by counsel. That alone sounds like a substantial improvement.