Those rough rankings are more about raw quality of the glass lens elements. And supposedly hold not just for photography and video/cinema but for other imaging as well. Medical, scientific, surveying, binoculars/field glass.
It’s the precise features of a given line from these manufacturers that would make a their lenses “great” glass. Nikon’s broad apature ranges, And especially small F-stops. Lieca being range finders. Canon’s success with long lenses. The engineering situation you describe with Nikon.
The quality of Nikon’s physical glass hasnt traditionally been as good as Zeiss’s. But all the other stuff with Nikon’s lenses elevates them to the same level. Canons lenses way back in the day do not seem to have been anything special. Comparable to 3rd party lenses, Minolta, Olympus, Pentax (but without the durability).
But Canon’s lenses from around the introduction of the Rebels and early dslrs were awful. Particularly the cheaper ones. I can’t tell you how many of those fuckers were returned as non-functional or damaged when I was selling this stuff. Cheap materials for the lens body. Plastic elements at glass prices. Visible glue everywhere. Including quite often on the main lens itself. Flimsy switches and focus rings. We used to check each one they sent to the shop for problems we were getting so many returns. And Canon stuff was about 80% of our repair business until Casio decided to sell digital point and shoots.
That was 10 years ago. In the meantime Canon has seriously improved manufacturing quality, materials, and fit and finish. Even as the engineering changes you mention has happened across everyone. The base quality of their elements have likewise seemingly improved. While Ive heard people complain that Nikon has slipped a bit. So now they seem about even. Differing mostly in precise features available in each mounting. I still don’t much like Canon. Most of the nifty fifty lenses I’ve handled have the same old excessive glue issue I used to see back when. Just doesn’t seem to impact function anymore. And I still find their white balance over does it on the yellow. Video I’ve never had as issue.
