I don't talk in games often (I don't send a message apart from "gg" and cooldown timers in most of my League games), and when I do I usually keep it game-related. For me, it's exactly like you said: I play the game to play the game. I don't like distracting myself with chatter when I want to win. I often "/mute all", or at least mute several players in the game, because of this.
That being said, I sometimes play without caring for victory. That's when I'll pointlessly converse or satirize the game and players. I see that as the other side of the coin: playing purely for fun. Honestly, I start feeling frustrated with players who are feeling like that when I'm not, and that's what mute's for. What I really see as pointless is negatively complaining about other players on your team: I see it as a paradox of wanting to win, but intentionally keeping yourself distracted with chatter.
The way I see it, the best way to talk over a game is to put yourself in an environment where players are less concerned about winning.