super-griek:
If in some specific case the use of that construction could cause any confusion, you'd better use the verb "igi", like this:

La instruisto igis la lernantojn skribi artikolon.

I totally agree, the sentence with "igi" is much better. The other one is confusing, it also made you confuse the object:
The object of "skribigi" is not the "artikolo", but the "lernantoj"

La instruisto skribigis la lernantojn.

Because it's not possible that one verb has 2 direct objects it's not possible to specify what was written, I think.