Homework problems were oftentimes deliberately difficult, and attending tutoring/office hours was almost certainly necessary for most students to master the material.
I got my hands on an instructor's manual of the textbook, and it was a tremendous boon for my mastery of the topics. By having immediate access to the solutions of difficult problems, I was able to comprehend how to approach problems of that type, and therefore could solve more difficult but similar examples in the future. The cycle of attempt/fail/check-solution/repeat was really effective. Waiting for the instructor's office hours or the availability of tutors would have made this process, if not impossible, incredibly inefficient.
Do any math educators have any insight to this? Is this math department clinging to an antiquated curriculum in which faculty is something of a gate-keeper to knowledge? Is there a good reason for their distaste for 'going around' them?