There are degrees here. Depends what kind of scotsman we are talking about. Having a general understanding of the uses of the tool, understanding what feasible

There are degrees here. Depends what kind of scotsman we are talking about. Having a general understanding of the uses of the tool, understanding what feasible in general, some best-practice rules of thumb and knowing how to google for details gets you most the way there. You could call that mastery. It certainly requires greater expertise than "I read a blog post and changed a few things until it seemed to work." But the bar is much lower than: is familiar with the source code; or even you can use the tool for common uses cases without recourse to the documentation. I think you do need to invest in getting over that initial learning curve such that your tools aren't "magic." You have a conceptual mental model of what is going on. And I agree that takes much more than a token effort. Yet for me, that also stops short of mastery.