A completely fair question, however, I think the problem with the question in question is then more about the generality/vagueness of it rather than it being a reference request (for which there is a tag)? Also, as the OP wrote in the question, he definitely respects and acknowledge that it may be considered too philosophical (in which case it was implicitly suggested that the question be migrated), and should (and have now done so) add 'broad' to that.
I think, to answer your question, book recommendation questions are (imo) on topic: tags for them (such as reference-request) exist on many other sites, and have been very useful for me as a user many times. I often find myself explicitly searching through others reference recommendations on stack, and I believe there's a reason for the tags to exist. I also think that even though no conclusion may have been made in the meta questions you refer to, I am not sure this question adds much more to the discussion. I e.g. agree with much of what is said here, and can see many of the problems with these type of questions as well. However, I still find those type of questions useful. Instead, we should really be explicitly discussing removal of the reference-request tag, or to include stricter requirements on such questions. As the tag reference-request exist, I think it's only fair to ask such questions, especially if being mindful about the possible vagueness it might take, and taking at least some precautions, and trying to be specific.
To conclude, yes (as this is a very opinion based question), but the real question should be about the broadness/vagueness many of these questions may take, and the question is then whether we can tolerate that in order to have the benefits such tags bring or not. I think both sides have their good points, but in the end I think there are natural reasons that such questions become quite common across the whole of Stack exchange, and I think many find them annoying, and many find them useful, so having a tag for them makes it easy to both ignore as well as focus on them respectively.
I also acknowledge that even though I may be part of the community as a whole, of mathematics.stack specifically, I am however very new to this site, and I respect fully if the cultures on different sites doesn't always coincide.
