I have no idea whether twas ever thus. It matches what I was taught in the 1980s. I went through a brief period of being a believer in the ceiling limits being mandatory when I first saw the AIP section. Wise voices talked me out of that belief, and I have now returned to my previous position.
As is so often the case, a simple concept is overcomplicated by poor drafting. Something the FAA by and large manages to get right.
2D