«أَهْلِ الْعُرْفِ»
People who speak according to common usage.
«الْأَوْسَاطِ»
Ordinary or middle-level speakers.
The reference is to people whose everyday utterances communicate meaning without necessarily attaining the highest rhetorical excellence. Their wording provides a useful picture of common expression, not an infallible measure for every occasion.
Treating an unusually wordy or inelegant phrase as the universal norm would distort the resulting comparison.