First, forcing children to solo-sleep was invented by the aristocracy. It doesn't come naturally (as evidenced by archaeological record, anthropological studies of primitive societies, and primate studies).
Second, none of the so-called benefits of child solo-sleep are supported by solid evidence.
Just because it became the "norm" in modern society is not sufficient reason to give it credence. We also used to push formula on infants because it was supposed to be better for them (my immigrant grandmother had a fit when she discovered that the hospital was feeding her drugs as a matter of course to stop her lactating). This policy was pushed by doctors and hospitals and public health officials for decades, with no evidence to support it (this is not a rant against medical personnel, but rather against procedural inertia without evidence - the very reason why we have the scientific method).
It's right up there with the bizarre America-wide policy of washing the protective film off eggs so that they now need to be refrigerated to prevent spoilage (and of course, every American "knows" that you must refrigerate eggs).
If you wish to push for something artificially induced only recently, the onus is upon you to provide extraordinary evidence to support it.