The problem I have with this is that it is akin to saying, "You can hit the wall all you like, but if the wall hasn't crumbled, you haven't really hit it."
There should always be some degree of collaboration involved. The student has a duty to try to learn. It is not a scenario in which the teacher is an entertainer to be appraised by the skeptical crowd at 'Education Idol' or some such — it is one in which the teacher is a conductor (at the very least) expecting some degree of compliance from an orchestra.
There are many other metaphors that will serves us well, but the 'go ahead, impress me, and if I haven't learnt — it's because you haven't taught' concept is rubbish.
Which brings me to the title of this post. The word 'reluctant' is not a passive one; the Latin reluctari means 'to struggle against'. A reluctant learner, like some I have encountered, is not a passive lump, but one who struggles against the teacher and the teaching process.
Nowadays, that unteachability is seen as a sign of 'independent thinking' and indeed seems to be considered a virtue. And so, we have reluctant teachers — teachers who must struggle against such silly ideas as accepting such thinking without critical evaluation.