Then people who are not in Steemit but had their work taken and used would not have the mechanism to flag someone so they cannot complain?

Lol, I'm not complaining about that. Flag them away! Destroy the plagiarists!

why would it be difficult to attribute and source then?

Well, if you don't know the source, Qurator says you shouldn't post the image, but I say you should just say "Hey, I don't know the source".

In fact, if you know the source, but it's not free to use, Qurator says you should not use it. I say you should just use it and try to find the author to attribute it to. Support them if you can. But don't think that you can't share something just because it's not allowed for commercial use.

I'm all for enforcing plagiarism rules.

I don't think so as I have seen posts that Steemcleaners or other people report such instances and a warning goes up.

I haven't seen that. I'd have to look it up. As far as I'm concerned, if it's obvious it's not yours and you don't imply that it's yours, then you shouldn't get retribution for seeming crimes.

So here you are exercising your right to copyright then

I'm against plagiarism. I'm not against posting a poem that I found, saying "hey, there's this author called Richard Goldmann who wrote this poem and I like it, I'll put it here". Commercial-use copyright laws would be against it, though, and would claim that I'm copying unlicensed work for commercial purposes (if the answer to the mother of questions, "Does Steem count as commercial use of content?" is yes)