Viper doesn't stonewall in feudal because he is an eco player that wants to save his stone for tc's. Only when it's really necessary will he make a tower/stonewall.My feeling is that Viper's pride makes him a bit different.
We saw Yo/Hera game, they are both comfortable to stone wall to defend against ultra-aggression, but Viper did not. Liereyy and Hera has enough micro to take advantage of that over-confidence.
EW is really punishing, small mistakes snowball fast.