When promoters ranked music previously, they simply made hundreds of personal calls to music store managers to ask their opinions of what the most popular music was being played or stolen. But as the technology of gathering data improved, the Nielsen Billboard changed over to tracking individual sales of albums and songs. What they found was wide gap in bias between what the music store managers were telling them and the actual sales of music.
Alternative music, throughout the 1980s was getting low scores, as well as rock, rap and country. But afterward more accurate methods to measure the individuals sales was put into process, the music industry had the wind knocked out of them. There was no ignoring the actual sales going on.