Everywhere one turns, the idea of disruptive innovation continues to spread, even as academics have cast doubt on the theory’s validity. Put on the agenda by scholars such as Clayton M. Christensen and Henry J. Eyring, the idea presumes that old institutions, including colleges and universities, will be hard-pressed to change fast enough to meet new external environments. Instead, new technologies and organizations will outcompete the old, even if -- and, in fact, because -- the new ones offer a subpar but cheaper product...