So, just to split hairs: Lemmy is a link aggregator, so it’s really better suited for this than Mastodon by design. BTW, please don’t make Mastodon a linkdump (I use that more than Lemmy) 🙂
Also, if you’re using a feed reader and Lemmy for news, then yes. There will be duplicates, but that is pretty much a problem in your setup, isn’t it? Can’t really fault either app for it.
All that said, I completely agree that just posting an URL without context or comment is unhelpful on any social platform. It’s always good to know what has motivated someone else to share a news item (especially in politics and other sports!).
I also agree that Lemmy (largely in imitation of Reddit) skews more social than just a link aggregator, so I’m not arguing you personally are doing it wrong. Tbh it feels more like an “everything forum”, but like I said — splitting hairs. That’s engagement, too 🙂
A tool or algorithm that hides or just deprioritises empty posts would certainly be useful, maybe even as a core feature in future releases of Lemmy?
For my part, I’d like to be able to hide posts based on the source URL [cough, screenrant, cough], same as blocking users or whole instances. Little, user-level filters like that could make a big difference in the individual experience.