This is a hotly contested issue in New Testament studies. There were probably two movements of debate that shifted the standard view.

Firstly there was a movement that argued that it was a common practice to attribute a document to another writer. There's no doubt this was true in antiquity - if you go through the large number of non-canonical texts written in Hebrew and Greek from about the 3rd century BC, most of them are claiming an authorship that is impossible to accept.

What the first wave or argument tried to do was show "this didn't matter much", i.e that false-attribution was a standard practice that no one took seriously and so everyone knew (for instance) that the deutero-Pauline letters weren't Pauline after all.

However a second wave of scholarship has come along (Bart Ehrman for instance) that argues that not only are these false attributed, but that false attribution wasn't acceptable to the early Christians, so that it is correct to call them forgeries.

I suspect that your ecumenical minister friend was trained and exposed to scholarship of the first kind, and not the second.

You will get a standard introduction to the issue of pseudepigrahia in any "Introduction to New Testament" textbook. Most commentaries on any individual book will give you a weighted opinion of the debate on that book's authorship.

Here's a link to an article arguing that the practice, when done with intention to deceive, was not considered acceptable, and so Deutero-Pauline letters are forgeries that weren't caught.

The bibliography is quite a useful place to go from there.

Essentially, yes there is some evidence of this practice of a student writing down the ideas of their teacher, but it is not widespread and probably isn't the correct parallel to the disputed letters of Paul.

I can't speak to NT texts specifically, but there are attested examples of this. Generally what happens is that the student's commentary on or expansion of the master's ideas gets transmitted anonymously (either intentionally, or because a mss circulated without a name), and later scholars erroneously attribute it on the basis of conceptual or stylistic similarity.

So eg, Ptolemy of Lucca wrote De Regimine, which was often attributed to Thomas because it is an obviously Thomist work. A number of the works in the Aristotelian corpus are now considered to be by his students. (Plato, of course, attributed everything to his teacher!) Fichte's Critique of all revelation was immediately attributed to Kant, but Kant was still living and credited Fichte. In China, long portions of the Zhuangzi are believed to have been inserted by later commentators.