The concept of universal mind was inherited by Buddhists from Hinduism which divided reality between spirit and matter (as does much Western philosophy) and sees mind as the work of spirit within the physical body.
The problem with that dualism is explaining how spirit/mind manipulates matter/body since surgeons had never found anything but boring goo in the human skull. That problem was comically addressed by Descartes in the 1600’s but didn’t start to find a real solution until the brilliant anatomical dissections of his contemporary Thomas Willis. See SOUL MADE FLESH The Discovery of the Brain — and How It Changed the World. By Carl Zimmer.
Darwin takes care of the rest. Since mind is no more than an accident of evolution reality is no more a mind than it is a pumpkin.
You could argue that none of this disproves the existence of a Universal Mind. It just makes it unnecessary.
It’s also possible that there’s a giant pumpkin (named Alfred, tho believers will debate that) in the centre of the moon.
The notion of universal mind is a distraction from the essential point—that the suffering, confused and seeking mind is already an integral part of universal reality. Thus the most immediate gate to reality is the mind itself. To me that is the great discovery of the first Zen people but the insight needs to be slightly refined, by discarding the notion of a universal mind.
My scanty reading of Lao Tzu et al has left me with the impression that they, like all mentally wakeful people, were aware that they were part of an incomprehensibly large and mysterious reality and that the trouble with humans is our tendency to regard that as merely a painted backdrop for the little drama of egos we call career, politics, history. They understood that the fundamental work of meditation is to return to our original, organic and wakeful attunement with That. They also understood that any attempt to weave doctrine or dogma out of that flow of attunement would only distract from it.
Better to let the seeker feel the flow by living, working and sometimes gabbing with people who are already awake to it.
As some sage once bluntly said, the philosopher who has not embodied his philosophy is an ass bearing a load of books. Probably it was contact between bookish Buddhists and such fundamentally wakeful persons that led to the kind of zen that rises from the clutter of words and letters, like an old (or young) ass dumping the books from his back.
I look forward to any opportunity to be part of that uprising, whether in life or art.
I write for the fun of it of course, but also because I know that this great uprising could happen
at any moment
even in the writing or the hearing of these words.