وأما ذكره فلكونه الأصل ولا مقتضى للعدول عنه
Explicit mention is also used because it is the normal form and there is no reason to depart from it.
Naming the subject is the normal way to make a predication intelligible. “خَالِدٌ حَاضِرٌ” (Khalid is present) identifies the subject without requiring a preceding exchange; “حَاضِرٌ” (Present) often needs context.
Omission is not inherently superior to mention. An explicit subject may be the most appropriate form whenever leaving it unstated would obscure which person or thing receives the predicate.