I might be able to explain the last part, since i’m guilty of it recently in a different regard.

I started a new community, !Imageedits!imageedits@lemmy.zip. To start a new community though, you need content. but the community type is intended to be users submitting content to edit, and myself and others edit as requested. I feel silly making posts just to complete them “for myself” and I’m too lazy to go look for interesting content to edit. So, I go to /r/psbattles or whatever, scalp a popular battle image, and post it to my community. along with an edit. makes me feel less silly while also generating some content that help showcase what the community can be used for. After I get maybe 1 page of stuff, slowly, I’ll post to a “new communities” area to advertise my community.

When people are pulling /reposting content from Reddit, its because they want to help Lemmy grow, and not just lurk, but they dont have any good new content to share. I would rather people repost here and there, and communities have content, versus everyone lurking, and OC slowly trickles in.