How lens flare went from a movie mistake to a sign of realism

Did you know that lens flare in movies is often a deliberate "mistake" meant to make a film more believable to the viewer? I didn't! That's why this video from Vox was so interesting to watch as it profiled the much-hated movie effect we are all so used to (and maybe even sick of) from its heyday as a real mistake in filming to something generated and added in by a computer.