"it's simply the conventions."

We were speaking of text grammar earlier.  This is a good example of the
advantage of being alert to text grammar.  In the above example, the
pronoun/antecedent relationship is not precisely between "it" and
"conventions."  Rather, it is between "it" and something beyond the present
material, perhaps a noun clause (stated or unstated) such as:  What is
unfamiliar to you . . . " which has a decidedly singular tone.  Thus, the
singular "it" is justifiable (sort of).

Jeff Glauner
Park University