As you implied, the point of such films is to press home a point, not tell a story. This is nearly always a mistake in any form of popular medium. I forget which Hollywood studio head said this back the '30s, but it’s still revelant: “If you want to send a message use Western Union.”
Also, these sorts of films are usually very low budget, acted by near amateurs trying their best, and directors with a “purpose” instead of a “vision”.
There are Hollywood efforts that are just as bad, though. These days it’s the left putting out films trashing some conservative or conversative ideas that are so over the top and silly you want to scream at the screen, “Really?!”
So anyone can be guilty of this, but it’s usually the sincere group with an agenda that makes this kind of mistake. They sacrifice good story telling for moralizing and it just doesn’t do what they had hoped, but rather puts people off.