A speaker may leave the subject unnamed so that, if challenged, there remains an opportunity to deny having referred to a particular person. This is called making denial possible (تأتي الإنكار).
أو تأتي الإنكار عند الحاجة
Or to keep open the possibility of denial when needed.
Suppose a known person is being discussed and someone says «لَا يُحْسِنُ التَّدْبِيرَ» — “[He] is not good at management.” The lack of an explicit name can make the intended reference easier to contest later.
This is an analysis of a rhetorical function, not an endorsement of dishonesty. Classical classification explains what the construction can be used to achieve; it does not by itself settle the ethical status of using it.