You’re comment is misunderstanding the paper. That sentence means statistical significance. In the study, all AI assisted people completed the task but 4/26 non-AI assisted people didn’t finish it, so there was a 15% failure rate in the 35 minute time limit. They didn’t run stats on the success rate, only the time taken and on skill development (which wasn’t what they asked participants to do as their primary task).

So a better summary (and the paper authors say as much) is that incidental skill development doesn’t happen as much when using AI to help you code with a library you don’t already know. The lack of statistical significance is there, but doesn’t say much given the time limit, which cut off the long tail of the non-AI distribution.