They do though, using on the oracles as in this posts example (which are level 30 enemies) a 331 is harder to kill them with than a 300 with disruptor. That's because they are doing the same damage without the disruptor perk, and then bonus damage for the 300 weapon with the perk applied. Take Vision of Confluence and Fang of Ir Yut (or any scout rifle with similar impact to VoC) and test them out.