Chess and basketball are both very clearly defined games*. The area of play, number of players, legal moves, and winning conditions are all clearly defined. There are definite beginning and end states, endings which cover win, lose, and draw.
* Don't argue about minor house variations, they are not official and are extremely minor compared to the openness of WoW.
WoW has none of these beside a starting point. We start somewhere, but what is the end of the game? What is the victory condition? There is no explicitly defined definition of winning. There are also a wider variety of legal moves.
With no defined win condition, there is also no defined way to win. This means that winning in WoW can only be decided individually. It could be a certain arena score, defeating the last boss, maxing out every rep, getting every pet, or being very (un)popular in trade chat. None of these are defined by the devs, the ones who make the rules, as wins. Nor as losses.
Think about that again: WoW has no defined win or lose in the overall game. A wipe or a lost BG/arena are losses, but neither are losses to the game as a whole. They would better be described as setbacks, the equivalent of the other team scoring, failures which are not actually defeat.
This does not mean that there are no wrong ways to play. There are some rules regarding cheating, abuse, and that sort of thing. But if your goal is to kill a kobold every ten seconds for an hour each day and you do that, you have won, by your own arbitrary definition of winning. Someone else may have a different definition and obviously they will take different actions.
Personal definitions will define action as well. Kobold Guy should not waste time in heroics, due to the lack of kobolds. That is, unless he has goals related to heroics (for simplicity, let us assume he does not). So in this way there are wrong actions or steps, but they are only those actions which do not advance a goal.
Personal definitions are not a free pass for anti-social behavior or an endorsement of nihilism. Kobold Guy should not be in your heroic searching for kobolds to kill, not only because he is wasting his time, but yours as well. Instead he should play either alone or with other kobold killers. Similarly, you should not bother him and his kobolds unless you have kobold-related goals.
Keep in mind that this doesn't mean there are no ways to compare players. If two guilds want to kill the Big Bad first, whoever kills it first is better (in some overall way, perhaps including luck or scheduling, but that's nitpicking). This means that if your goal is ego inflation, Kobold Guy is a valid comparison, if you wish to go kill kobolds faster and therefore think you're better. Go for it, I bet you can beat Kobold Guy's kobold kill record. That doesn't mean his goal is wrong, though it may mean that he's bad at killing kobolds.
A person cannot be bad at WoW, but they can be bad at what they attempt in WoW. Take note of the difference the next time you're looking to tell someone they're doing it wrong.
P.S. This isn't a justification for playing badly or for screwing with other players. When goals and actions do not align, figure out a solution, even if that means going to another place. Elitist whining about how they're doing it wrong fixes nothing.