I just don't understand in what sense verbing nouns per se can be considered either a "mistake" or a mistake.
Would you not consider it a mistake to use a verb (or any word) that is not found in any dictionary or even used in any dialect?
Not automatically! Consider the following sentence:
"It's not a good idea to build an engine around Tribute because, even though it can act as a village, its nonterminalness is unreliable."
Was it a mistake for me to use the word
nonterminalness in that sentence? if so, why?
Verbing a noun can mean entirely novel constructions, like nonsense words,
On that level, almost
every linguistic act is an "entirely novel construction". The noun isn't novel, and the act of verbing nouns isn't novel; though the act of verbing a
particular noun may be novel, language is
all about combining a finite set of elements into an unlimited number of novel constructions.
except that the root noun allows someone to interpret the meaning.
Yes. So why should it be considered a mistake?
(Note: I'm not contending that any
individual instance of verbing a noun might not be a mistake for one reason or another. But "English allows for 'mistakes' like verbing nouns" makes it sound like you're saying that verbing nouns can be characterized in some sense as a mistake
in general, which is what I take exception to.)