Is there a reason you believe people have this unintuitive plot in mind, rather than simply conflating with the difficulty of physically scaling a steep slope?
> a reason you believe people have this [...] plot in mind
Sample size N += 1, HTH, HAND.
So a "learning curve" that is "steep" implies that learning occurs rapidly; a "forgetting curve" that is "steep" would be "in one ear and out the other".
Super pedantic and I don't plan to change my use of steep learning curve, but I get where the intention is coming from.
[1] https://www.psychestudy.com/cognitive/memory/ebbinghaus-forg...
I imagine that one could spend a long time learning the fundamentals before getting to a stage where the proficiency escalates quickly i.e. where the steepness occurs. But the long time getting there is what the term "steep learning curve" is about. Like the opposite of taking a long run at jumping off a cliff. I'm sure that this is easier to show with a graph.