As someone who really only went on Reddit for memes and techie discussions, I think I can say this: for my use-case, there was nothing special about Reddit itself. In fact, one thing I have realized is just how little the nature of the host matters beyond ease of use. Sure, certain formats lend themselves better to certain use-cases, but ultimately humans are social creatures, and even in the most inconvenient of circumstances, we find a way to make it work.
And once you realize that, it becomes less about the medium, and more about the people who lead the discourse. From what I can gather, Reddit lost that discourse a long time ago. And as such, their downfall was only a matter of time.