. Manufactures don't want to take the extra time and money to do something like that. And besides, it would be horrible luck if they actually made money if you destroyed your engine and had to buy a new one from them (sarcastic).

I think a carburetor the MFG would have to design wouldn't be worth the extra cost. $1 added cost can be a lot in manufacturing sometimes. Manufactures aren't concerned about safety. They are concerned about making money. Their lawyers are concerned about safety, that's why you get disclaimers and instruction manuals. If the MFG thought that adding a closing carb would gain them money then they would add it and you would see a marketing add about it.