Bull****. It is not enough to simply intend or discuss a crime. There must be action. You are attempting to run the Thought Police and have therefore abrogated any claim to justice.
At least one of these people never acted.
Wrong. Attempting to incite a riot, the evidence of which was gathered electronically, is sufficient actus reus for a properly-defined offense.
Conspiracy charges, attempted charges, etc are well-founded in criminal law in several Common law nations (US included). The UK appears to have an offense of "encouraging or assisting crime" on the books, which replaced incitement. Regardless, Common law also has provisions for party to an offense, accessory to an offence, and aiding/abetting. All of these are considered actions for the purposes of criminal law in Common law countries.
Short answer: planning a crime is also a criminal offense in many situations, even if the original crime was not actually committed. That's true in the US, UK, Canada, and Australia (to name a few).