It's said there are no new ideas, which I totally don't believe. But, there's no denying that a lot of the basic ideas have been done and done and done again.
And even if the basic concept isn't new, as long as the rest of it is, then it's original. Look at all the superheroes out there. Many of them have much the same basic concept, but because the rest of them: Their appearance, their personality, their general backstory, power, etc are all different they are totally different characters.
So people who get hot and bothered over something similar to theirs needs to take a reality check. BUT, a tracer is just down right diabolical. They are deliberately stealing the design and selling it as their own. They aren't even really being thieves they are just being copy cats and liers.
My art can't really be stolen, technically. But, I am a bit leery about showing people how I do my banners. Frankly, I just use Gimp to make my banners and once you get the technique down it's really not all that hard. Plus, I've got all my Layer stock on my DA free for anybody to use. So, someone could potentially start making banners almost exactly like I do and sell them as their own, claiming they made the technique and such.
And I'm not that great at putting myself out there, not nearly as well as these scam artists can be, so I'd definitely be pushed out, lol. I guess, I'm more worried about my technique being stolen then my art itself. Though, I would be really rather annoyed of someone used a Banner I made for someone else. I expressly say the banners aren't for open use if they aren't, so.