Good point, though I do believe that there won't be often a case like the one you mentioned. I always try to be friendly to everybody, my Teammates and my opponents and therefore I want to be able to give a little shoutout to the players opposing me that act fair and sportsmanlike or those who made the game more enjoyable through other means (eg. a lively and well manered chat).
It doesn't necessarily have to influence the honour Level, but be more of a nice gesture towards those players that make this game great.
Sure, it won't change the Toxicity of the playerbaae significantly, that's something only reports can do, and believe me, I do report often.