From Wikipedia’s entry on Ancient Geek Sculpture:
By the early 19th century, the systematic excavation of ancient Greek sites had brought forth a plethora of sculptures with traces of notably multicolored surfaces, some of which were still visible. Despite this, influential art historians such as Johann Joachim Winckelmann so strongly opposed the idea of painted Greek sculpture that proponents of painted statues were dismissed as eccentrics, and their views were largely dismissed for more than a century.
In other words, some dudes let their prejudices prevail, and vehemently dismissed a bunch of other people who interpreted evidence and came up with reasonable conclusions, and it took a century before those narrow-minded dudes were contradicted by science. Remember that next time someone less dynamic than you calls you an eccentric and denies something for which you have clear evidence.
“Influential” doesn’t always mean “right.”