What you say is true, but it's not the main issue IMHO. Rather, it's that people rip copyrighted materials whole-cloth and post them as CC.
I produce short videos for a client, on a moderate budget. I was using lots of CC and public-domain labeled stuff from archive.org and YouTube. Then I realized, "Hey, wait! This TV show from the '50s is *not* public domain! Neither is this educational film from the '70s!"
This is what comes from people misunderstanding the slogan, "Information wants to be free." You get ignoramuses thinking, "Yeah, and I'm the one who'll set [someone else's stuff] free." There's a word for that -- theft. And that's what sadly permeates collections of "CC/PD" content