I fully expect mass posting like that will be the norm on Lemmy, even more than it was on Reddit. Now instead of a handful of subreddits that cover similar context, there are also a handful of communities on here with literally the exact same name. As annoying as it is to see a bunch of duplicate posts in my feed, I can't say I blame users for doing that when communities are often fragmented here.

I really think despite that we don't have overall karma, people still get off on getting highly rated posts. I mostly lurked on Reddit, but would occasionally post something and I can't deny that I enjoyed seeing the post get a lot of upvotes. But here on Lemmy, I became a mod of a couple communities and I post a lot and I've noticed I don't even pay attention to the scores at all. I think one reason is since I post a lot more, I don't pay attention, and also the scores don't generally get as high, due to the smaller userbase. But I agree, people need to get out of that mentality of trying to get the highest rated post scores. It really makes it much more enjoyable to get involved in discussions, IMO.

gosh it isn’t “narcissist” to not “check the latest couple dozen posts

"I just discovered this thing, and since it's new to me I immediately conclude that no one else has seen it either because the horizon of my reality extends no farther than the diameter of my own head"...is absolutely narcissist.

The opposite of narcissism is considering that other people exist, and that other people might have found it and posted it first, and to assume they have until you do some minimum amount of diligence to find out. That minimum amount of diligence is just checking for recent posts on the same topic - it's not rocket science - it's just having the basic minimum amount of social-awareness to consider there are other people in that community who may have already posted it.