I don't think that's right, and the example given in the article seems to agree with me. The 7s&8s are indeed counted, indirectly: the score is the percent of all responses (including 7s&8s) that are promoters minus the percent of detractors.
So, using your example, 990/1000=99% of people are passive, 7/1000=0.7% are promoters, and 3/1000=0.3% are detractors, so the NPS score is 0.7-0.3, or 0.4 (not 40). Passives aren't a part of the last calculation, but they affect the percent values for promoters and detractors.
So, using your example, 990/1000=99% of people are passive, 7/1000=0.7% are promoters, and 3/1000=0.3% are detractors, so the NPS score is 0.7-0.3, or 0.4 (not 40). Passives aren't a part of the last calculation, but they affect the percent values for promoters and detractors.