It was the dialog
"Qué penses-tu de ce restaurant, Helène?" - "Moi, j'aime beaucoup."
In English and other languages, this wouldn't work without pronoun: I like a lot -> I like it a lot, so I would have expected something like "je l'aime beaucoup".
My question: does it depend on the verb, i.e. you can always use aimer without the object being liked, or are there other reasons why it works here, but might not elsewhere?