(What I don't really understand is why US conspiracyism limits itself only to things that don't exist - you don't hear so much about Watergate, Iran-Contra, COINTELPRO and so on.)
There's an easy answer: you can't wildly speculate when you have the facts. This is why "PizzaGate" is still being talked about. There will never be proof, because it's a ridiculous conspiracy. That leaves the conspiracy enthusiasts free to hunt for evidence and clues forever.
It's almost tautological: once we know something happened, it's no longer a conspiracy. Therefore, conspiracy enthusiasts will no longer care about it.
This. If there is a solid answer to the question then you can't have the pleasurable hobby of fitting puzzle pieces from different sets together to point to the coming apocalypse.
That's... not actually what "conspiracy" means.
"conspiracy (noun): a secret plan by a group to do something unlawful or harmful"
This article is just a great description of the network of people discussing the idea, not an an actual analysis of this theory in light of Merkel's actions.
We can't know what the intentions in her heart are, but if she's not deliberately trying to destroy Europe she's certainly running it into the ground.