Hot take, but that guideline is just bad. It removes necessary context and may even obscure relevant developments in a public dialogue. Original posts make sense only if the repost is not adding to the dialogue or otherwise making interesting contributions.
(If you disagree, this may the one time I will actively ask you to flag this post, so a mod can respond to this point)
This. Whenever I post a comic and something funny comic on Twitter/FB (i put credit: URL their home page or IG), but on Reddit, there is no such thing. Most Reddit admins also ban direct linking to sources due to spam or remote server overloading. So instead, you need to use Imgur or Reddit's hosting. So I write a comment saying credit which often gets enough upvotes to push at the top of the thread. I think those content creators deserve traffic and recognition too. It is good karma for everyone.
Citing the guidelines is against the guidelines, if not by the letter, in spirit. It's boring and it lacks curiosity. It assumes too much about the sharer. "Can we stop this trend" is a dog whistle for the "HN is getting worse" complaint.
Instead we could be considering if we're meant to read the Twitter conversation as well, or sharing a laugh about the link in the tweet author's bio. Or maybe the sharer didn't feel comfortable enough seeming like they made the claim but still wanted to share it because it's kind of cool.