It's a simple but effective strategy. Secretly co-opt every random idea, symbol, and fad you can, in every single form of media out there, even if you don't have an immediate use for them, because it builds up an "arsenal" of triggers that can be activated later whenever it's convenient.
It's the memetic equivalent of the old spook tactic of installing sleeper agents in thousands of random but otherwise innocent organizations. Most will never be activated in their lifetime and only a handful will ever be used, but simply by flooding the target environment with agents you ensure that you always have someone in the right place at the right time. This has the added bonus that the patsy organization/idea takes the flak while the puppet masters slink away.