Is it me, or does Imgur seem to have a near-monopoly that's enforced by the mods in the major subreddits?

I've run several experiments to see if this might be true. At various times I've tried submitting images to r/pics, r/funny, r/wtf, etc... Nearly without fail, in the instance I used a host that wasn't imgur the image would get filtered out or promptly deleted after posting. Mind you, this happened even when the image was directly linked. But when I submitted through Imgur... lo and behold everything went fine. I'm gonna go a little tinfoil here, but I'm starting to wonder if the mods are getting a piece of the action from Imgur.