Recently there have been a couple of deviants that have complained about other deviants or just people in general on the internet who steal their work.

I agree that in most cases it's some sort of stealing, even if it can't really always considered stealing. It's copying. And there's a difference in that. Of course, posing someone else's work as your own isn't ethical.
Somehow people think that by posting something on the internet with a © mark prevents others from using it. That nonsense. If it's good and attractive, no matter if it's a program snippet, an image or a sound file, someone will use it. Wether they choose to ask for permission or not or to pay or not is another question.
Ripping isn't dangerous, using someone elses work as base to create a new piece is OK too. In fact, you could modify someone elses work to a degree where it's not even considered to be owned by the person that creates that base-property.
If you are afraid your work will be used by someone else - don't post it online.

Of course there are regulations ans such, but there is an inherent difference in making a copy and using an physical item.
But the internet is not harmonized in legal terms, and that means that is in most cases unclear who is supposed to folow what laws, as well as which of all the possible laws really do apply.

Now if someone is using your work in print for commercial uses, like for a magazine, advertising etc, that's a somewhat different matter.

Cheers.