Two recent movies, based on actual historical events, brilliantly depict illustrative, startling, and dramatic examples of large numbers of people engaging in willful blindness - and the Cassandras who finally changed things. Labyrinth of Lies shows Germans in the 1950's acting like the Holocaust never happened. Spotlight shows just how many people knew or should have known about Catholic clergy abusing children sexually, and also shows that the higher-ups kept moving pedophile priests from parish to parish - and for a long time no one did much of anything about it.
Facing problems is almost always better than sweeping them under the carpet for the purpose of furthering group harmony. As long as a problem is invisible, it will remain unsolved. As James Baldwin once said, "Not everything that is faced can be changed, but nothing can be changed until it is faced."