any new idea will be treated as a variant of something the listener has already thought of or heard.

From a Bayesian point of view, this is as it must be. People have priors and will assess anything new as a diff (of log-odds) from those priors. Even understanding what you are saying, before considering whether to update towards it, is subject to this. You will always be understood as saying whatever interpretation of your words is the least surprising to your audience.

BTW, this is standard in natural language processing (which is what a lot of Schank's AI work was in). When a sentence is ambiguous, choose the least surprising interpretation, the one containing the least information relative to your current knowledge.

The narrower your audience's priors, the more of a struggle it will be for them to hear you; the narrower your priors, the more you will struggle to hear them.

Having shown how Schank's Law is but an instance of Bayesian inference, I trust you will all find it acceptably unsurprising. :)