On the absence of flat star clusters

Taylor has asked the question why there are no flat star clusters. A useful starting point might be a paper by the late, great Donald Lynden-Bell, "Can Spherical Clusters Rotate?", in which he breaks with the tradition that the answer is always "no" if there is a question mark in the title and points out that a spherical cluster of mass points may rotate without becoming oblate. Gaia results indicate that at least some globular clusters rotate, but with no evidence of a link between rotation and flattening.