Thank you for this. Interesting, isn’t it?
There is a clue to this as well in reading through Nikon’s “Thousand and One Nights” series on lens design. It’s a good series to read through and think about. They slip in a lot of details for various aspects of lens design and implementation that, if I’m paying attention, lead to some understanding of what they were doing and why.
A lot of discussion about vintage lenses ignores the importance of coatings. Lens coatings are supremely important, not only to limit lens flare but to prevent loss of contrast from reflected light bouncing around diffusely. This recent article from PetaPixel has some nice example images.
Lens coatings are constantly developing, in tandem with optical design. Some vintages lenses had decent coatings for their day, but multicoatings are continuously becoming more and more complex, as the technology to produce them reliably develops, so now a $200 lens gets coatings that were only available on top lenses a few decades ago (if at all).
Unfortunately, lens manufacturers rarely (if ever) discuss the fine details of their coatings. Element diagrams do not nearly tell the whole story even to experts.
Also, I read that digital cameras add a new problem: the glass above the sensor is still a bit reflective (despite its own coating) and bounces light back to the rear lens. If this back of the of the lens is not coated, it itself bounces back some to the sensor, reducing contrast. No such problem (and no such coating) with film-era lenses.