I didn't say that the grammar is more important. - I said that I took the view grammar was not less important.
I don't separate the two "compoment" of the language.
So, if you don't know the grammar, you won't be able to use that so many words what you know. In addition if you don't know words, expressions, phrasal words and so on, you won't be able to use your grammatical knowledge.
For example if you meet a special sentence...for example "I should have thought you knew." and you don't know what mean the should have done structure, you won't be able to translate - or you will if the context helps you.