In lesson 4.8, there is brief mention that “prepositional pronouns” can be used without prepositions to emphasize the person in question. This is one of the examples:
Invito lui alla cena, ma voi no.
(I) am inviting him to dinner, but not you.
It is confusing to me that “lui” and “voi" in this example are considered “prepositional pronouns.” Grammatically, they are acting as direct objects, not objects of a preposition, so why call them “prepositional pronouns”?
I see that in Italian they are called “forma tonica.” Would it be correct for me to internalize a rule that the “forma tonica” is used for both direct objects and objects of a preposition? If so, I will just forget about the name “prepositional pronoun” which seems inaccurate and confusing.
Thank you!