It is from Iron and Wine song "Innocent bones". As a non native English speaker, I struggle to understand the exact meaning. It is thoroughly a grammatical question.
- Does it mean that, because everyone is singing about things they lack, "we" simply sing about love, and lack nothing? or
- Does it mean that everyone is singing about things they lack and "we" too sing about a thing we lack - love?
I think I do not understand the meaning of "so" in this sentence.