OK, instead of saying "this is tricky" people should say, "this will take some practice." I got pointers right away but it took a lot of practice to use them without error.
The author completely missed the point about why teachers say "this is tricky". It's not about telling students to pay attention, they do that if they want. And it's certainly not about telling people it's so hard they need not bother.
It is to make it OK for students to not understand right away and not feel bad about asking questions.
I was trying to be brief, but that is essentially what I meant to say...perhaps I'll edit to clarify that. I think the effect is still the same, though, regardless of the motivation behind the phrase.
