What does 1 Chronicles 21:3 mean?

But Joab pushed back against the king, saying, 'Why do you want to do this? Aren't the people of Israel already your people, no matter how many there are? Why should you make the whole nation guilty by insisting on this count?' 1 Chronicles 21:3 - Modern Text Bible

(Joab is warning David that counting the people could bring guilt on Israel, hinting at a deeper spiritual problem with David's motives.)