I think we agree on a lot of things which aren't vocabulary. Well, that and jewel box full of Easter eggs. I have no idea wth you mean or why non designers would care. But you've touched upon one of my biggest gripes, the difference between simplification and reduction. A simplification organizes information into useful patterns so that it can hide away redundancy. A reduction cuts information for the sake of presentation. Reduction can feel like simplification because the end result is a nice crisp aesthetic, but the difference is apparent when you try to use it. Its like the difference between tidying your room and throwing all your stuff out.

My go to case and recent obsession is the NYC subway map. Here is the 1970s Vignelli map.
https://mymodernmet.com/wp/wp-content/uploads/2021/01/massim...
Here is the map that has been in use for the last 40+ years.
https://new.mta.info/map/5256

Designers tend to love the Vignelli map, but everyone in the city hated it and it was short lived. To this day you can still hear condescending remarks like the Vignelli map was "to abstract for NY". "NY choose the worse map". But its exactly like you said, first and foremost the point of design is to download information into brains, and by that metric the current map is far superior which is why it won.

Consider the background geography. Ardent supporters of the London Tube / Vignelli style insist surface streets are clutter full stop. Maybe that reduction of information makes sense in London and Europe where streets are a mess anyway, but in a grid city that reduction doesn't make sense. The present map simplifies the streets down to just a few representative examples so you know the local orientation of the grid and have a few reference points. Simplification, not reduction. The information is still there.

The coloring system is another massive example of simplification. The Vignelli map seems to hate information compression, insisting every line have its own color and own dots. The current map reduced clutter by organizing lines by where they run in Manhattan, denoting the express/local difference with black/white dots. Personally I think that symbol could be less arbitrary, but most people have no trouble figuring it out quickly. Its a simplification down to a single line which makes everything fit in a tight space while being easy to follow. There have been changes in service patterns which have ruined parts of the current map, but the very original version had some nice symmetry to it (and mostly still does). Even though the rule is technically "color by Avenue in Manhattan", that rule lined up with certain repeating "color zones", eg both South Bronx and Flatbush being Green/Red, Upper West side and New Lots being Blue/Red etc. You could sort of count on certain colors to be associated with certain broadly defined endpoints.

Perhaps, this example, being so utterly detached from the modern web design world, is one you might use simply because no one has any personal stake in it. Its a lesson designers should learn more often. Hiding and removing != simplifying. Good != pretty. Organize information well and its often close to pretty on its own.

(I have plenty of gripes with the present map but that's for another time)