putting aside accessibility, I believe that the usefulness of icons boils down to brain efficiency.
Considering that the brain has hard-wired neurons (since birth) to automatically count/recognize up to 3 objects, we need some icons as anchor points. With emphasis on some.
You can have max of 3 icons in a row, and a max distance of 6 items without icons.
Then you can VERY quickly find any menu item, by doing "+/-3 from X anchor" math, which your brain does extremely efficiently.
Further, this means that an action is represented by a relative path (e. g. save as = 1 down from the save icon). This further helps the brain to store these associations, because it's also extremely efficient at storing relative paths. So, long time users automatically become more and more efficient at using your software.
Considering that the brain has hard-wired neurons (since birth) to automatically count/recognize up to 3 objects, we need some icons as anchor points. With emphasis on some.
You can have max of 3 icons in a row, and a max distance of 6 items without icons.
Then you can VERY quickly find any menu item, by doing "+/-3 from X anchor" math, which your brain does extremely efficiently.
Further, this means that an action is represented by a relative path (e. g. save as = 1 down from the save icon). This further helps the brain to store these associations, because it's also extremely efficient at storing relative paths. So, long time users automatically become more and more efficient at using your software.