Yes but that doesn't mean they have permission to do so. And if you see it happening you should report it as a good fan. They ought to know better and if they don't it's the perfect chance to educate them on the law and the ONE request the creator that gave us this amazing fandom at all has asked of us--don't sell shit without his permission.
I suppose so. I'm not gonna report every freaking thing that's Homestuck related on etsy since its not really my job or my problem. They should know better than to sell that, but I suppose if they don't, someone will tell them eventually.