Destra Ruthlessness

I played a 2s game a decent while ago.  Late game, it was down to me and another player. I was AR and he was TL.  He began to spam corvettes, making a fleet of approx. 160+.  I thought of trying something new instead of the standard flak defense, so I created a fleet of Destra Crusaders with Ruthlessness, which does 1.5 DPS (non-stacking).  I figured Ruthlessness coupled with a relatively small flak fleet would be able to take out his vetts.  However, I quickly discovered that Ruthlessness does not affect corvettes.  My question is simple: Why?  

I understand Titan AoE's not affecting vetts because vetts are supposed to be counter.  However, as compared to Destras with Ruthlessness, Titans and vetts are relatively early game vessels.  You rarely - if ever - see a player with Ruthless Destras before seeing a player with a Titan.  

Essentially, I think it would make sense that vetts should be immune to Titan abilities but vulnerable to abilities found on Cap ships, frigates, or cruisers.  Am I alone on this front, or does it seem to be a reasonable demand?