Here's the thing.
Even if you look at things from an occult perspective, symbols and images only have the power you give them. If they are promoting them, it's less to seduce kids to the dark side. 'cause most of those kids just seem those symbols are something cool, or weird, or something that pisses off their parents. At best, the power they attribute to it is shallow adolescent rebellion. The fear/disgust/hatred that people on forums like this have for such imagery would feed any occult ritual far more.
I take a more cynical approach to this sort of things though. It's a distraction. Nothing more, nothing less. The powers that be know that sites like this will gasp and point at all the evil they are being shown but not really doing shit about it so they keep feeding more weird shit to more or less have a continuous feedback loop of the producing content, someone noticing it, bringing it to attention to their favorite conspiracy forum, causing discussion rather than action... Rinse and repeat.
What people don't realize is these symbols don't really have any real effect on the kids. Lord knows openly more overt satanic imagery didn't do crap to me. Parents have more effect on their children than they believe or their kids admit. Be a good parent and your kid will turn out good.