I feel like the graph is a poor choice in illustrating this idea. As it's central to the argument, the rest of the article falls apart, in my eyes.

First - why do both graphs start the user with 0% performance? Humans come into a new program/context/etc with prior experience. Put a child who's used Word before in front of ed, and he'll probably do well. Put him in front of vim, and he'll probably struggle to write a sentence.

Second, not all performances are created equal. The dependent axis should probably be some measurable output. Typically, something with a "steep learning curve" takes longer to master, but has much greater payout in the end. (If it doesn't, people generally don't learn it.) Compare making TV Dinner with cooking a family meal. The TV dinner is easier to learn, easier to master, but having "100% performance" in making TV Dinners is still not on the level of being even a good cook.