Metaphysical speculation can be fun and can be aesthetically satisfying, so there is nothing in principle wrong with it. But it has more in common with religion than with science. If you ask on a science forum whether the idea of a common mind is true, most people will say "no", or, if they want to be more philosophically accurate, they will say there is no evidence for the idea and thus it has no place in science. This leaves the door ajar for those who want to speculate in a non-scientific way, which is fine. But, if you say is it true that quantum field theory says there is a single Mind, the answer is a resounding NO, absolutely not, it is utter rubbish.