We grade various Archetypes A B C etc. There are some “sweet spots” in certain Archetypes, where that combo is better than the average grade for the Archetype, … or worse. Power sets and builds that really make the most of that Archetype, or really suck. You can probably list a few in your head. Corruptors are the only Archetype where every single combo is an S class character.
S is a grade from the Japanese gaming systems and is higher than an A. Yes, EVERY Corruptor is an S class character. They tend to do different things, but they bring to the table solid DPS, and (depending on powersets) solid buffs, debuffs, heals, etc. Whether solo or on a team these characters pivot from support to DPS as needed, and perform great in both roles. Yes, there are better support characters. Yes, there are better DPS characters. No, no other Archetype is as versatile and powerful.