I know nothing about Waldorf but I have worked in a Montessori preschool for several years.
I don't agree that the children all work alone on their own and emphasis is not on socializing. Our rules were that a child pick their work and do it on their own mat/table. However if another child comes over and wants to join that child then they must ask and if the child with the work says it is okay then they do it together. If the child says "no thank you" or "not now" then that is respected. I always likened it to an office setting. If you are working and do not want to be disturbed that is okay and if not that is okay too.
There is another part I don't agree with but no time now.
Also, I can't get a real sense of what Waldorf is from this article so had a hard time comparing its aspects to Montessori. I guess I'll have to look it up.
Laurel