She did not quite say that. She said that it was only practiced by monastic elites up until the early 20th century:

"Meditation was not at all a mainstream lay practice in Buddhism. It only became popular in the early twentieth century, when Buddhist reformers such as the Burmese monk Mahasi Sayadaw, founder of modern Vipassana meditation, promoted it as a lay Buddhist practice. Mindfulness, as it was practiced for most of its history in Asia, was a very elite practice reserved only for advanced monastics."