A lot has to do with the perceived intent. If the Redditor thinks they are karma farming something intentionally used before, pitchforks.
I’m more annoyed when people post something and are like “I dont know if this is a repost or not but here”
If you didn’t create it yourself, then it’s a repost. Why would you assume a meme you saw on Facebook or Instagram wasn’t already posted on MassimoL
“The principle of the thing”
Its annoying/infuriating to see someone stealing the thing that you made to take credit for it