This in a nutshell, more or less.
I'd add that the problems were already there since the very beginning, because both Superman Returns and MOS were rushed productions which started for reasons which don't have much to do with a real plan, mostly to avoid legal actions from Siegel and Shuster's heirs.
There was a lot of incompetence too, too many cooks in the kitchen (or no cook at all sometimes), and even some bad luck along the way (Ezra Miller...). But what is comically bad about the entire slate of DCEU movies is that for literally every single one of them they tried to change the approach, in an endless series of course corrections mostly focused on what they DIDN'T want the movies to be like, or what they wanted them to resemble, rather than what they wanted the movies to BE like.
Superman Returns relies too much on dull Donner nostalgia? Ok, let's make Superman more similar to Nolan's trilogy, let's put Nolan among the producers and make Superman more aggressive and sexy - heck, let's put half-naked Cavill in half of the movie and let's make some female characters openly say that he IS hot, because viewers are too dumb to realize it themselves. This is not your grandfather's Superman, pal!
MOS didn't work? Maybe Superman doesn't work in solo films. OK, you know what - let's put Batman in the sequel or even better, let's include BOTH Batman and Wonder Woman. Just to be sure let's kill Superman, too.
And since someone criticized the darkness of the movie and the fact that it was too long let's butcher Suicide Squad.
OK, the previous movies were considered too dark, you know what? Let's make Wonder Woman a bit less dark, maybe it will work.
Heck, IT WORKED! Let's make the Wonder Woman sequel even LESS dark, or even better - let's make it as dumb as possible and let's get Steve Trevor back in a ridiculous subplot which doesn't make sense.
And so on. And on. Of course, this is an oversimplification and there have even been some positive moments here and there, but the fact that this joke lasted for almost TEN years (15, if you include Superman Returns) is beyond my understanding.