Ah, I see. Thanks for the clarification.
This is still a case of apples and oranges. Whereas the NASB (and KJV and NKJV) has all words I italics which are added for readability or clarity, the original NIV (1984) added a few brackets around words and phrases only "if there was uncertainty about such material" (quoted from the "Preface"; emphasis mine). In the case of the verse you cited above, there is uncertainty about the legitimacy of the "It is said" (some translations have "You say"). In the NASB's case, the italics indicate words that are added for clarity or readability, but in the NIV's case, the brackets are added not to show where they've made the text more readable or clearer, but to show where they are uncertain about certain words added for clarity or readability.
If you compare the NASB with the original NIV, you will find it to be the case that the NASB still has a lot more italics, and that the original NIV does not indicate everything (or even most things) they have "added" to the text to promote clarity or readability (e.g., look at "his" in Job 21:32).