Actually, in my opinion, the biggest thing hurting esports is the flux. 3 years ago, esports could mean playing well different games than today, or than it will in 5 years. At least it has started to crystallize into MOBA, FPS, RTS (dead
). But who's to say that a new genre won't pop up in the next 10 years that changes what people want to play and watch?
Add on top of that there are constant changes being made to the games being played, because they need to be kept interesting for general audience, and it's really not optimal for long term competitive scene. Imagine if the association changed the size of the playing field or ball weight or size of the goalposts every month in soccer. Sports mastery is less about exploration (adaptability) and more about exploitation (using experience and learnt knowledge), but so far, esports is too much about adaptability to changes.
The closest that comes to stability is CS:GO. But it's starting to show age, and correct me if I'm wrong, the viewer rates for that game are dropping. But even there they add new maps and remaster old maps, which just changes the experience, both viewer's and player's.
In short, there is no standard for "What is esports" other than "playing computer games competitively", which is currently too broad.