Reddit “stuff” isn’t automatically crossposted here. You’ll only see it when users decided to do that themselves. There are a number of communities that are equivalent to subreddits but the content in them is all new. Lemmy doesn’t have any direct feed to Reddit content.
I think I’ll remain agnostic on that one. Ask me again in 50 years and I’ll probably know the answer by then. Unless I happen to somehow reach the age of 106 without dying, in which case I’ll take a raincheck.