Competitave games like Dota 2 or Starcraft contain a very competitative element. You are divided into tiers of skills, either a direct MMR number (Dota) or rough groups (Starcraft). Both give you a good chance of seeing how well you stack up against the average player and how very very far you are from the very best.
Such a clear score is very hard to ignore for naturally competitive people like me. And so the game can become a grind, where it's all about the MMR points. The whole "fun" thing becomes secondary. Which is sad, because we play games for the fun of it. If something gives you no pleasure, you're under no obligation to do it and it gives you no money then why do it?
Lately I've been focusing more on the whole fun part of the game. It makes losing far less frustrating, because now you don't think about how much you failed or how horribly bad your teammates were. You think about that moment in the game where you did something epic, amusing or just plain badass. Whether that was a long distance arrow scoring a kill, a crit doing insane amounts of damage or force-staffing a teammate into the enemy fountain.
It also makes me want to pick charachters for what I think will be fun instead of trying to go with optimal picks. First of all, I'm not good enough to even know what optimal is. Secondly the level I play at is very different from the level professional games play at, and what would be great pick there may very well not be a great pick at my level. And finally, such "optimal" heros can quickly become non-fun. Being unable to do anything because you're an underleveled support with no escape mechanism is very frustrating. Causing me to play risky, dying and then becoming even more frustrated.
Playing for fun is more fun. Who would have guessed?