this is actually quite brilliant. and articulates the value and utility of subjective forecasting-- something i too find somewhat underrated-- extremely clearly and convincingly. and same goes for the biases we have toward reducing things to a mathematical model and then treating that model as more "credible" despite there being (1) an infinite universe of possible models, so you can use them to "say" whatever you want anyway and (2) it complects the thing being modeled with some mathematical phenomenon, which is not always a profitable approach.

the scribble method is, of course, quite sensitive to the number of hypotheses you choose to consider, as it effectively considers them all to be of equal probability, but it also surfaces a lot of interesting interactions between different hypotheses that have nothing to do with each other, but still have effectively the "same" prediction at various points in time. and i don't see any reason that you can't just be thoughtful about what "shapes" you choose to include and in what quantity-- basically like a meta-subjective model of which models are most likely or something haha. that said, there's also some value in the low-res aspect of just drawing the line-- you can articulate exactly what path you are thinking without having to pin that thinking to some model that doesn't actually add anything to the prediction other than fitting the same shape as what is in your mind.