Of course everybody knows the right way to convince conspiracy theorists that they're wrong is to go after them. I don't see what's wrong with having internet trash bins. At least the trash is in a know location, it doesn't spill everywhere. I'm not from the US, the only mentions of those sites I have ever encountered was journalists making a few articles about them.
I think this line of thinking is absolutely correct when conspiracy theories are fringe or harmless. You don't believe we landed on the moon? Okay, buddy, have a nice day. Occasionally, though, conspiracy theorists escape the harmless fringe and become actively harmful to society, which is what many of us believe is happening in the USA today. A racist conspiracy theory that posited, contrary to all evidence, that ou…
One could look toward China's internet policy to measure the success of playing "whack-a-mole" at the rumor-level. Propaganda there still gets made and spread, it just stays online for minutes at a time before deletion, and so by the time people see it they have no way of asking for clarification on its truth.