Okay, here I go. I've composed myself here.
We as a community have been discussing Turf War in depth since the release of the game. Ink or Sink was the main tournament that decided a lot of things for us. People hated Turf in IoS, as proven by the game of Turf Chicken played in the semifinals.
In summary, Turf war is easily swung in the last few seconds of the game. It didn't exactly matter what you did for the first 2:30 of the game; it came down to the last 30 seconds and which team could use their specials to wipe the other team and gain the most turf to claim victory.
This special roundup is what makes Turf not competitive. That's why nobody uses it competitively, because it's not fun competitively. Heck,
@luigisly made the comment last night asking "How would you even commentate this?" (in reference to Turf). It's ultimately not fun for a few, not spectator friendly, and ultimately not a mode suited for competitive play.
So, There you have it. Because we decided this like 3 months ago. If you want to make your own Turf war tournaments, feel free to do so, but don't expect any top teams to sign up. Also, don't say the word "Competitive" in reference to your tournament. Because it's not. Sorry, that's the way it is. If you would like to, many threads have gone to this very topic. Go ahead and browse them to see how extensive we've gone through this.
And if you for one second think that the results of your Turf war tournament will be counted in any competitive rankings, I suggest you think again. Because they won't be.