Reddit IS a forum platform. Anyone who wants to create a subreddit can do exactly that. Reddit did not replace forums, just the software that they run on.
Reddit is distinctly different from a typical forum due to how heavily it weighs time and popularity. A normal forum can have multiple threads of thought active at the same time without interference, and sometimes a thread can live for a long, long time. There's no need for a thread to be super popular to survive, a thread can literally live off of two users.
On reddit, if the time is not right, the discussion will not be had and ends up in oblivion.
