At the same time, language evolves and changes. Expecting it not to is likely only to lead to frustration. (I'm not immune. "Steep learning curve" to mean something difficult to learn gets me a bit riled.) The change you observe here is back formation[0], I believe.
Now, if you'll please excuse me. I think there are some kids on my lawn.
>(I'm not immune. "Steep learning curve" to mean something difficult to learn gets me a bit riled.)
This has exactly the same effect on me. I've always thought about skill acquisition in terms of RC time constant: the time it takes me to reach 63.2% of something is finite and infinitely smaller than the time it takes to reach 100% (which never comes, hence the infinitely smaller), sometimes a sigmoid pops into my head.
So when I heard the expression "steepest learning curve" for the first time, I thought "sweet! tau is really small! Heaviside function like skill acquisition."
My brain melted when the context that followed the expression suggested that the thing was "really hard". "But.. but.. you have a Dirac like rate".
I use it sometimes but I give offerings to the Gods asking for forgiveness.
The original formulation is based on a skill acquisition vs experience chart. On such a chart, a steep learning curve is one where skills are acquired quickly, as opposed to skills that are difficult to acquire. The common "steep learning curve" = "difficult" usage is understandable, given that steep hills are more difficult to climb. It's a knee-jerk reaction for me so it's transient: you're not going to see steam coming out of my ears :)
At the same time, language evolves and changes. Expecting it not to is likely only to lead to frustration. (I'm not immune. "Steep learning curve" to mean something difficult to learn gets me a bit riled.) The change you observe here is back formation[0], I believe.
Now, if you'll please excuse me. I think there are some kids on my lawn.
[0]: https://en.wikipedia.org/wiki/Back-formation