Yes there does. Many forums I go to double post and they have no problem with it. I would have never known the moderators are against it if you never told me. If the moderators here say you shouldn’t do it, than it should be in the FAQ.
And why should things not be taken seriously? The OP now has to wait a week to get the answer to his question. If I were in the OP shoes, I’d be pretty aggravated. It’s rude. And if it’s out of sarcasm, it’s still cruel behavior.