The author is partly right on the right that it was a cultural response to war.

Here's a relevant excerpt from the book Dutch Graphic Design, A century of innovation. (2006. P. 76-81).

"De Stijl was one of many critical intellectual responses to the calamity of World War I. [...] This aim was implicit in De Stijl's first manifesto, published in 1918:

'There is an old and a new awareness of time. The old is based on the individual. The new is based on the universal. The struggle of the individual against the universal is manifesting itself in the World War as well as in contemporary art.... The war is destroying the old world with its contents; the dominance of the individual in every sector.'

In 1921 a similar sentiment followed in the fourth volume of De Stijl:

'For Europe there is no longer any way out. Centralization and property, spiritual and material individualism was the foundation of the old Europe. In that it has caged itself. It is falling to pieces. We observe this calmly. We would not want to help even if we could. We do not want to extend the life of this old prostitute.'

De Stijl advocated an idealistic goal to liberate art from nonessential and outdated qualities such as subject matter, naturalism, subjectivity, and decoration. Its diverse advocates rejected outright what they saw as the sentimentalism and degeneration of the nineteenth century. They expressed a desire for a new rational art that better suited the modern world, a 'collective impersonal style.... destined, they felt, for adoption by architects and designers of the machine age." They were not, however, a 'lost generation'; instead they enthusiastically espoused a new industry-based culture. In order to meet the needs of a new epoch, the members of De Stijl advocated a revision of old understandings of beauty which had been based solely on craft. They realized that twentieth-century technology could be utilized to create a union of art and industry. In October 1917 Van Doesburg wrote in the first issue of De Stijl:

'It is the endeavor of this small magazine to make a contribution toward the development of a new consciousness of beauty. It desires to make modern man receptive to what is new in the plastic arts. It desires, as opposed to anarchy and confusion, the 'modern baroque, to establish a mature style based on pure relationship of the spirit of the age and expressive means. It desires to combine in itself contemporary ideas on the new plasticity, which, although fundamentally the same, developed independently from one another.'"

Similar thoughts were shared in most artistic and other cultural movements of the time. However, how this managed to be so successful is rarely analysed. My hypothesis is this: these kinds of anti-ornament movements were advocated by both socialist and capitalists. For socialists mass-produced functional goods meant that everyone could have equal amounts of decent quality stuff. For capitalists it meant the opportunity to increase the surplus value of goods when productive time wasn't "wasted" on inefficient ornamentation.

For both—socialists and capitalists—ornamentation was an obstacle. They wanted a complete cultural shift, where by devaluing tradition, craft and ornamentation, people could br untied from their locality like their home, village, town etc., and thus much easier relocated to new industrial areas (like big cities). Mass produced goods meant that you could move and simply buy fresh new things (because they were cheap). It also meant that you weren't attached to your things (like you would if you spent time on crafting them yourself), so it didn't matter if they were beautiful, they just had to work.