For all the pedantics that just wanna hate without actually learning about what's happening in the industry, here's the skinny:
CN's run by idiots.
To elaborate, they're mainly concerned about filling time slots and maximizing "toy sales." I put "toy sales" in quotes because that's their given reason for any time anything gets canceled; never mind the fact that the merch just isn't there in the first place, but that's a whole other point.
SO, how do you fill time slots? Reruns. You can't rerun a strictly plot-centric, or they don't think you can anyway, because they're worried about:
A - Spoilers
B - Confusing their audience.
- they think people are too dumb to realize that if the drop into the middle of something it's not going to make sense. Unfortunately this is true in many cases, but that's a another topic.
Justice League Action was supposed to be an episodic action show; an attempt to fulfill the "we want action shows," claims by viewers, while adhering to CN's ridiculous Air Time -to- Production Value target rations. Obviously the result is that it doesn't have a plot, each episode is really empty, and nobody gives a fuck about it. It's literally there in the title. "THIS IS THE JUSTICE LEAGUE, AND IT'S GOT ACTION, COME WATCH IT!"
Bit of a misnomer that people want "Action Shows;" what those people want is something meaty, something with a story and conflict and consequence that they can tune into and get invested in. This directly conflicts with CN's agenda of filling as much air time as possible with as little cost as possible, because they're a sinking ship trying to run a station in 2017 like it's 1998.
The obvious result is to make a show that's got a plot, but like a 2-to-5, Filler-to-Plot content ratio, so that they can have something to fill time with, and basically run as commercials for the other episodes, so that people will want to come back for more of that.
The master strat would be to then start their own steaming contracts.