I see unacknowledged poems, pictures, quotes, jokes almost every day on social media. Most of the time, The moment I see something copied, I doubt. I do a simple search, and almost always, it turns out that I was right! Even if you have never seen the original thing, It is not difficult to identify because If you know someone, you know what kind of things they can write. Also, when people start praising you on a copied poem - how can you not say that it is not written by you but someone else?! I find it amusing. I have massive respect for people who cite others' work. I used to think that it is normal but not anymore.
Given the craving for attention, it is no wonder that it is on the rise. Cutting and pasting without citation might not be wrong or a big deal on social media - but if you do it ...remember that the people you are trying to impress with that kind of thing are not worth impressing because they are foolish enough not even to figure it out that it is copied ! and others recognize it immediately that you copied and it backfires. Anyways. It is what it is.