I would ask if you really understand the organization of lines at a university. If you do not, then you're missing more than can be explained in a few sentences.
There are substantial duties outside of teaching and research. Tenure obligates faculty to some of these (eg- committee work) and frees them from others.
Additionally, many pillars are required to build stable colleges. A tenured faculty member has to have some measure of generalized aptitude and capability in addition to deep specialty and institutional knowledge. Many spend increasing time fighting their "other duties" and neglecting others as they approach retirement, placing burdens on their peers who have their own obligations or have taken on additional responsibilities in the college to juggle time for pay.
Good deans understand and attempt to manage this so they don't lose the faculty they would like to keep before an opportunity arises for the productive contributors to become tenured or tenure tracked. They stewards, past and present, who rely on information not available to the faculty at large.
Not being tenured doesn't necessarily mean you're poorly compensated or not highly valued, but it's a point of pride some can't swallow when they've given many years to an institution and have stalled in trajectory because their university couldn't justify adding a new line to their department. It's not about them, they know it, and the type of people who can't accept that, knowingly and incorrectly assign blame, and take everyone down with them like the author above are exactly who you want to protect the college from ever entering a tenured role.