Why enumeration comes from sitemaps here
A collector pointed at the search on this site comes back nearly empty and the usual conclusion is that the source is protected. It is not; it is simply built so that discovery happens through published sitemaps rather than through crawlable listing pages.
Reading the sitemap first turns a difficult crawl into a simple one, and the per-course sitemaps do more than list addresses - they describe what each course contains, which is exactly the material inventory a client wants and would otherwise have to assemble by walking pages.
The second reason this source is unusual is that the materials themselves are published - notes, problem sets, exams and reading lists, not just descriptions of them. That makes it one of the few sources where a client can build something on the content itself rather than only on statistics about it, and it makes material typing and the per-course licence field a functional requirement rather than an afterthought.
The third is curriculum research. Two decades of syllabi from one institution, with terms and years attached, is a record of how a curriculum changed - what was added, what stopped being taught, how a subject's reading list drifted. That question is hard to answer anywhere else with this consistency.
The fourth is scope. This is one university, and a strong one, which makes it excellent for depth and unrepresentative for anything claiming to describe higher education generally.