What amazed me about that particular sub was the masterful propaganda it provided. It goes so far that not even the heavy users realize how much they deceive themselves. How? This way:
It was always very, very heavily moderated. They don't delete comments, they simply ban users. Anything that looks like dissent or not agreeing with the current (subject to change) political opinions and lines from Trump will get banned right away. And the comments will get deleted. Lots of users of this forum reported they were banned themselves, even if they are ardent fans of Trump. Just because they happened to deviate from the line an inch or so one time.
This breeds complience. Thus even the most bullshit articles will only have cireclejerk comments. Since the expectation on Reddit is that bullshit content will get called out in the comments, because all subs work like this, this exception to that rule makes the outrageous bullshit content, which is mainly weird conspiracy theores (Trump also frequently peddles conspiracy theories) believable. So much so, that I think the users deceive themselves that the shitposts of QAnon, Seth Rich, Pizzagate, Project Veritas, etc. are real or in any way credible.
Quite amazing. It's a breeding ground for pure ignorance. If you want to find out about bad effects the internet is having on democracy and society, /r/the_donald is prime research material.