"The INTJ is also notoriously unsocial, displaying the limited Fi range of expressions. They have no problem with people, but they don’t feel any immediate and pressing need for them, except those they have already adopted into their heart. Like the ISTJ, the INTJ very much loves who they love, and I have experienced this very genuine love and friendship from several INTJs in my life, as well as ISTJs. What it lacks in outward expression it makes up for in its endearing sincerity." - Michael Pierce
Source: Pierce Presents: INTJ | CelebrityTypes
Yes, that is one of my favorite quotes but I think the act of comparing INTJs to ISTJs is kind of bad. Perhaps a more accurate statement would be to refer to certain ISTJ variants.