
"Where does fluff fit in this game?"

This type of player feels more at home in the presence of stiff competition and generally do well in tournaments as their ability to construct powerful lists and maximizing the output of their army generally pertain to much more solid chances in "random" situations (this random referring to the idea of not knowing who or what army you'll be facing in tournaments).
This type of player generally knows how to play the game very well. In many ways they may have mastered some aspects of the game. Their skills may become the current "meta" if done well enough, and this is truly a testament to this ability to think in ways others may not.
vs.

When playing the game, often times we'll see somewhat less potent units and/or combinations being used in order to attain a better story. These players often use units deemed "bad" from the online meta. Units will generally play smart, but may often not stand up in comparison to meta-strength units.
Generally these players seem to feel more at home in the beer and pretzels style game with friends. This isn't to say they can't enjoy or do well in the tournament scene, but many times their lists may not sand up. These players may utilize units that are custom made and may or may not fit the correct scale or size in order to allow for more hobby (larger bases or taller/shorter models).
Now I'm not saying that these are the only two types of players. These are examples from the somewhat extreme ends of play. I personally feel like I sit in the middle and float between the two feels. I try to create lists that follow the fluff, but these units are generally pretty potent units. I avoid bad units (as I know I am competitive) but will try to utilize units as they would be in the fluff.

In the end we all can play how we see fit. There is not really a right or wrong way to play. I'm interested to see where people sit on this particular discussion.
Cheers!