That's still crossposting. The only difference is aesthetics. No convenience would be worth what we would lose. The diversity of the internet is what makes it worthwhile. It would be a nightmare as far as harassment. Being able to mass-post across any & all sites with one click would make having distinct sites pointless. It would mean a homogenized internet which would lend itself to corporations/gov't controlling it all. It's against the spirit of the internet.