Promotion: What You See Now IS What You'll Get in the Future; Dossiers are often "fishy"--Imagine a Sarbanes-Oxley where the dean had to sign off on a dossier and not only their dean memo! Finally, there is not enough room at the top.
I have of late reviewed the scholarly literature in higher education on promotion and tenure, of which there is remarkably little.
1. What you see is what you will get. In general, the best predictor of future performance of an assistant professor, if tenured, is what they did during the probationary period. Much less often there is a late bloomer, much more often there is an early decline. (As far as I can tell, there is no literature on what happens to those who are denied tenure. Do they thrive elsewhere?)
2. Associate professors are often loaded down with administrative work, and that slows their progression to full, or delays it for a very long time. Some choose this path, but that is a different matter.
3. The biggest problem is the "fishy" dossier. Whether it be misrepresentation of achievements (were you really the PI on this grant?, is this book a scholarly book?) or "stinking" letters of reference (people had not read the work, they were "pinkie"-length rather than arms-length, or members of a "club"), the committee, departmental, or dean's memoranda do not take account of the problems. [Here the issue is that the university promotion committee will have someone on that committee who happens to check up on things, or notices misrepresentations or letters that share a paragraph word for word. That stigmatizes the case, and often marks the dean as someone who is not reliable, from whom you would not buy a used car.]
Deans could be required to sign off on a dossier, as well as their dean's memo, ala Sarbanes-Oxley.
There is one other problem, that of publishing in the main journals, and or prominence. If you count the number of people up for tenure who are expected to publish in the main journals, there is not enough room in those journals for their expected number of articles. And if you count the number of places where people are expected to be the leading two or three (or ten, or even twenty) figures in a field, again there is not enough room at the top. By the way, the mathematicians call this the pigeonhole principle, the social scientists call these "positional goods." In Lake Woebegone everyone is well above average.