Resource-recommendation questions are very hard to handle, and they were in fact deemed completely off-topic for several years until we managed to work out a consistent policy that lets the good stuff in without wreaking havoc. The result of the policy is at
Are resource recommendations allowed?
and you should read it carefully (and ideally its previous revisions and their links to other questions here and elsewhere on the network and the Stack Exchange blog) to get a sense of where the rules come from. In particular, Good list, bad list gives a good sense of what the problems are with unrestricted resource-recommendations questions.
One of the problems, specifically, is that if those questions are allowed to have arbitrary 'level' specifications, it spawns an unchecked granularization that renders them useless. Thus, if you allow "books about rotational kinematics for undergraduates" in addition to "books about rotational kinematics" in general, why not "books about rotational kinematics if I'm halfway through my analytical mechanics" or "books about rotational kinematics for undergraduates but don't use fancy math", or.... . This makes all of the questions less useful, and it takes a definite toll on the signal-to-noise ratio of the site in general.
Thus, we tend to err on the side of making questions as coarse-grained as possible. If you don't like it, sorry: this site is not meant to be (and cannot be) all things to all people, and when some class of questions directly harms the site's ability to fulfill its core aspects, then those questions get restricted.
For your specific question, my feeling is that the proposed duplicate contains plenty of resources that address what you're looking for (and thus your new question would be harmful fragmentation of the existing lists). If you feel this isn't the case, you can offer a bounty on the old question asking specifically for answers that emphasize a certain subtopic.
If you want to propose a change in policy, you're welcome to do it, and this meta is the place to do it. However, as always, if you do it without understanding the problems that the existing structures were meant to solve, and providing alternative mechanisms to cope with those problems (or arguing conclusively that they're not actually problems), then your policy proposals will be of very little use indeed.
